diff --git a/answer_callback_query.go b/answer_callback_query.go
index 3a65e4a..287b2a2 100644
--- a/answer_callback_query.go
+++ b/answer_callback_query.go
@@ -2,6 +2,7 @@ package telegram
 
 import json "github.com/pquerna/ffjson/ffjson"
 
+// AnswerCallbackQueryParameters represents data for AnswerCallbackQuery method.
 type AnswerCallbackQueryParameters struct {
 	// Unique identifier for the query to be answered
 	CallbackQueryID string `json:"callback_query_id"`
@@ -29,6 +30,8 @@ type AnswerCallbackQueryParameters struct {
 	CacheTime int `json:"cache_time,omitempty"`
 }
 
+// NewAnswerCallbackQuery creates AnswerCallbackQueryParameters only with
+// required parameters.
 func NewAnswerCallbackQuery(callbackQueryID string) *AnswerCallbackQueryParameters {
 	return &AnswerCallbackQueryParameters{CallbackQueryID: callbackQueryID}
 }
diff --git a/answer_inline_query.go b/answer_inline_query.go
index fb9996f..968a507 100644
--- a/answer_inline_query.go
+++ b/answer_inline_query.go
@@ -2,6 +2,7 @@ package telegram
 
 import json "github.com/pquerna/ffjson/ffjson"
 
+// AnswerInlineQueryParameters represents data for AnswerInlineQuery method.
 type AnswerInlineQueryParameters struct {
 	// Unique identifier for the answered query
 	InlineQueryID string `json:"inline_query_id"`
@@ -35,6 +36,8 @@ type AnswerInlineQueryParameters struct {
 	IsPersonal bool `json:"is_personal,omitempty"`
 }
 
+// NewAnswerInlineQuery creates AnswerInlineQueryParameters only with required
+// parameters.
 func NewAnswerInlineQuery(inlineQueryID string, results ...interface{}) *AnswerInlineQueryParameters {
 	return &AnswerInlineQueryParameters{
 		InlineQueryID: inlineQueryID,
diff --git a/answer_pre_checkout_query.go b/answer_pre_checkout_query.go
index 58a5f6a..630a526 100644
--- a/answer_pre_checkout_query.go
+++ b/answer_pre_checkout_query.go
@@ -2,6 +2,8 @@ package telegram
 
 import json "github.com/pquerna/ffjson/ffjson"
 
+// AnswerPreCheckoutQueryParameters represents data for AnswerPreCheckoutQuery
+// method.
 type AnswerPreCheckoutQueryParameters struct {
 	// Unique identifier for the query to be answered
 	PreCheckoutQueryID string `json:"pre_checkout_query_id"`
@@ -19,6 +21,8 @@ type AnswerPreCheckoutQueryParameters struct {
 	Ok bool `json:"ok"`
 }
 
+// NewAnswerPreCheckoutQuery creates AnswerPreCheckoutQueryParameters only with
+// required parameters.
 func NewAnswerPreCheckoutQuery(preCheckoutQueryID string, ok bool) *AnswerPreCheckoutQueryParameters {
 	return &AnswerPreCheckoutQueryParameters{
 		PreCheckoutQueryID: preCheckoutQueryID,
diff --git a/answer_shipping_query.go b/answer_shipping_query.go
index a2a00cf..a67d786 100644
--- a/answer_shipping_query.go
+++ b/answer_shipping_query.go
@@ -2,6 +2,7 @@ package telegram
 
 import json "github.com/pquerna/ffjson/ffjson"
 
+// AnswerShippingQueryParameters represents data for AnswerShippingQuery method.
 type AnswerShippingQueryParameters struct {
 	// Unique identifier for the query to be answered
 	ShippingQueryID string `json:"shipping_query_id"`
@@ -22,6 +23,8 @@ type AnswerShippingQueryParameters struct {
 	ShippingOptions []ShippingOption `json:"shipping_options,omitempty"`
 }
 
+// NewAnswerShippingQuery creates AnswerShippingQueryParameters only with
+// required parameters.
 func NewAnswerShippingQuery(shippingQueryID string, ok bool) *AnswerShippingQueryParameters {
 	return &AnswerShippingQueryParameters{
 		ShippingQueryID: shippingQueryID,
diff --git a/constants.go b/constants.go
index 25108b4..2eca8cb 100644
--- a/constants.go
+++ b/constants.go
@@ -1,5 +1,9 @@
 package telegram
 
+// Version represents current version of Telegram API supported by this package
+const Version = 3.6
+
+// Action... represents available and supported status actions of bot
 const (
 	ActionFindLocation    = "find_location"
 	ActionRecordAudio     = "record_audio"
@@ -13,6 +17,7 @@ const (
 	ActionUploadVideoNote = "upload_video_note"
 )
 
+// Chat... represents available and supported chat types
 const (
 	ChatChannel    = "channel"
 	ChatGroup      = "group"
@@ -20,6 +25,7 @@ const (
 	ChatSuperGroup = "supergroup"
 )
 
+// Entity... represents available and supported entity types
 const (
 	EntityBold        = "bold"
 	EntityBotCommand  = "bot_command"
@@ -34,6 +40,7 @@ const (
 	EntityURL         = "url"
 )
 
+// Method... represents available and supported Telegram API methods
 const (
 	MethodAddStickerToSet         = "addStickerToSet"
 	MethodAnswerCallbackQuery     = "answerCallbackQuery"
@@ -96,11 +103,13 @@ const (
 	MethodUploadStickerFile       = "uploadStickerFile"
 )
 
+// Mode... represents available and supported parsing modes of messages
 const (
 	ModeHTML     = "html"
 	ModeMarkdown = "markdown"
 )
 
+// Mime... represents available and supported MIME types of data
 const (
 	MimeHTML = "text/html"
 	MimeMP4  = "video/mp4"
@@ -108,11 +117,13 @@ const (
 	MimeZIP  = "application/zip"
 )
 
+// Scheme... represents optional schemes for URLs
 const (
 	SchemeAttach   = "attach"
 	SchemeTelegram = "tg"
 )
 
+// Status... represents available and supported statuses of ID
 const (
 	StatusAdministrator = "administrator"
 	StatusCreator       = "creator"
@@ -122,6 +133,7 @@ const (
 	StatusRestricted    = "restricted"
 )
 
+// Type... represents available and supported types of data
 const (
 	TypeArticle  = "article"
 	TypeAudio    = "audio"
@@ -138,6 +150,7 @@ const (
 	TypeVoice    = "voice"
 )
 
+// Update... represents available and supported types of updates
 const (
 	UpdateCallbackQuery      = "callback_query"
 	UpdateChannelPost        = "channel_post"
diff --git a/delete_chat_photo.go b/delete_chat_photo.go
index cbfb3c3..d61763d 100644
--- a/delete_chat_photo.go
+++ b/delete_chat_photo.go
@@ -2,6 +2,7 @@ package telegram
 
 import json "github.com/pquerna/ffjson/ffjson"
 
+// DeleteChatPhotoParameters represents data for DeleteChatPhoto method.
 type DeleteChatPhotoParameters struct {
 	// Unique identifier for the target chat
 	ChatID int64 `json:"chat_id"`
diff --git a/delete_chat_sticker_set.go b/delete_chat_sticker_set.go
index 5759681..0aab3dc 100644
--- a/delete_chat_sticker_set.go
+++ b/delete_chat_sticker_set.go
@@ -2,6 +2,7 @@ package telegram
 
 import json "github.com/pquerna/ffjson/ffjson"
 
+// DeleteChatStickerSetParameters represents data for DeleteChatStickerSet method.
 type DeleteChatStickerSetParameters struct {
 	// Unique identifier for the target chat
 	ChatID int64 `json:"chat_id"`
diff --git a/delete_message.go b/delete_message.go
index 3e9bbda..c4e57b0 100644
--- a/delete_message.go
+++ b/delete_message.go
@@ -2,6 +2,7 @@ package telegram
 
 import json "github.com/pquerna/ffjson/ffjson"
 
+// DeleteMessageParameters represents data for DeleteMessage method.
 type DeleteMessageParameters struct {
 	// Unique identifier for the target chat
 	ChatID int64 `json:"chat_id"`
diff --git a/delete_sticker_from_set.go b/delete_sticker_from_set.go
index d9e4ecc..20445f0 100644
--- a/delete_sticker_from_set.go
+++ b/delete_sticker_from_set.go
@@ -2,6 +2,7 @@ package telegram
 
 import json "github.com/pquerna/ffjson/ffjson"
 
+// DeleteStickerFromSetParameters represents data for DeleteStickerFromSet method.
 type DeleteStickerFromSetParameters struct {
 	Sticker string `json:"sticker"`
 }
diff --git a/doc.go b/doc.go
index 323e289..a8a896a 100644
--- a/doc.go
+++ b/doc.go
@@ -1,2 +1,2 @@
-// Version of the bot API: 3.6 (February 13, 2018)
+// Package telegram contains bindings for the Telegram API
 package telegram
diff --git a/edit_message_caption.go b/edit_message_caption.go
index 9db0809..522215c 100644
--- a/edit_message_caption.go
+++ b/edit_message_caption.go
@@ -2,6 +2,7 @@ package telegram
 
 import json "github.com/pquerna/ffjson/ffjson"
 
+// EditMessageCaptionParameters represents data for EditMessageCaption method.
 type EditMessageCaptionParameters struct {
 	// Required if inline_message_id is not specified. Unique identifier for the
 	// target chat or username of the target channel (in the format
diff --git a/edit_message_live_location.go b/edit_message_live_location.go
index f38d8dc..7a96b67 100644
--- a/edit_message_live_location.go
+++ b/edit_message_live_location.go
@@ -2,6 +2,8 @@ package telegram
 
 import json "github.com/pquerna/ffjson/ffjson"
 
+// EditMessageLiveLocationParameters represents data for EditMessageLiveLocation
+// method.
 type EditMessageLiveLocationParameters struct {
 	// Required if inline_message_id is not specified. Unique identifier for the
 	// target chat or username of the target channel (in the format
@@ -26,6 +28,8 @@ type EditMessageLiveLocationParameters struct {
 	ReplyMarkup *InlineKeyboardMarkup `json:"reply_markup,omitempty"`
 }
 
+// NewLiveLocation creates EditMessageLiveLocationParameters only with required
+// parameters.
 func NewLiveLocation(latitude, longitude float32) *EditMessageLiveLocationParameters {
 	return &EditMessageLiveLocationParameters{
 		Latitude:  latitude,
diff --git a/edit_message_reply_markup.go b/edit_message_reply_markup.go
index 9039fae..c63467c 100644
--- a/edit_message_reply_markup.go
+++ b/edit_message_reply_markup.go
@@ -2,6 +2,7 @@ package telegram
 
 import json "github.com/pquerna/ffjson/ffjson"
 
+// EditMessageReplyMarkupParameters represents data for EditMessageReplyMarkup method.
 type EditMessageReplyMarkupParameters struct {
 	// Required if inline_message_id is not specified. Unique identifier for the
 	// target chat or username of the target channel (in the format
diff --git a/edit_message_text.go b/edit_message_text.go
index 32753b6..e25f0b3 100644
--- a/edit_message_text.go
+++ b/edit_message_text.go
@@ -2,6 +2,7 @@ package telegram
 
 import json "github.com/pquerna/ffjson/ffjson"
 
+// EditMessageTextParameters represents data for EditMessageText method.
 type EditMessageTextParameters struct {
 	// Required if inline_message_id is not specified. Unique identifier for the
 	// target chat or username of the target channel (in the format
@@ -30,6 +31,7 @@ type EditMessageTextParameters struct {
 	ReplyMarkup *InlineKeyboardMarkup `json:"reply_markup,omitempty"`
 }
 
+// NewMessageText creates EditMessageTextParameters only with required parameters.
 func NewMessageText(text string) *EditMessageTextParameters {
 	return &EditMessageTextParameters{
 		Text: text,
diff --git a/export_chat_invite_link.go b/export_chat_invite_link.go
index abd5f95..291be82 100644
--- a/export_chat_invite_link.go
+++ b/export_chat_invite_link.go
@@ -2,6 +2,7 @@ package telegram
 
 import json "github.com/pquerna/ffjson/ffjson"
 
+// ExportChatInviteLinkParameters represents data for ExportChatInviteLink method.
 type ExportChatInviteLinkParameters struct {
 	// Unique identifier for the target chat
 	ChatID int64 `json:"chat_id"`
diff --git a/forward_message.go b/forward_message.go
index 9c756aa..752c495 100644
--- a/forward_message.go
+++ b/forward_message.go
@@ -2,6 +2,7 @@ package telegram
 
 import json "github.com/pquerna/ffjson/ffjson"
 
+// ForwardMessageParameters represents data for ForwardMessage method.
 type ForwardMessageParameters struct {
 	// Unique identifier for the target chat or username of the target channel (in the format @channelusername)
 	ChatID int64 `json:"chat_id"`
@@ -16,6 +17,7 @@ type ForwardMessageParameters struct {
 	MessageID int `json:"message_id"`
 }
 
+// NewForwardMessage creates ForwardMessageParameters only with reqired parameters.
 func NewForwardMessage(from, to int64, messageID int) *ForwardMessageParameters {
 	return &ForwardMessageParameters{
 		FromChatID: from,
diff --git a/get_chat.go b/get_chat.go
index 4c81d24..9142a1c 100644
--- a/get_chat.go
+++ b/get_chat.go
@@ -2,6 +2,7 @@ package telegram
 
 import json "github.com/pquerna/ffjson/ffjson"
 
+// GetChatParameters represents data for GetChat method.
 type GetChatParameters struct {
 	// Unique identifier for the target chat
 	ChatID int64 `json:"chat_id"`
diff --git a/get_chat_administrators.go b/get_chat_administrators.go
index 30b64a3..9434dc8 100644
--- a/get_chat_administrators.go
+++ b/get_chat_administrators.go
@@ -2,6 +2,8 @@ package telegram
 
 import json "github.com/pquerna/ffjson/ffjson"
 
+// GetChatAdministratorsParameters represents data for GetChatAdministrators
+// method.
 type GetChatAdministratorsParameters struct {
 	// Unique identifier for the target chat
 	ChatID int64 `json:"chat_id"`
diff --git a/get_chat_member.go b/get_chat_member.go
index 8703178..b81cc2a 100644
--- a/get_chat_member.go
+++ b/get_chat_member.go
@@ -2,6 +2,7 @@ package telegram
 
 import json "github.com/pquerna/ffjson/ffjson"
 
+// GetChatMemberParameters represents data for GetChatMember method.
 type GetChatMemberParameters struct {
 	// Unique identifier for the target chat
 	ChatID int64 `json:"chat_id"`
diff --git a/get_chat_members_count.go b/get_chat_members_count.go
index 2355966..140193c 100644
--- a/get_chat_members_count.go
+++ b/get_chat_members_count.go
@@ -2,6 +2,7 @@ package telegram
 
 import json "github.com/pquerna/ffjson/ffjson"
 
+// GetChatMembersCountParameters represents data for GetChatMembersCount method.
 type GetChatMembersCountParameters struct {
 	// Unique identifier for the target chat
 	ChatID int64 `json:"chat_id"`
diff --git a/get_file.go b/get_file.go
index ba66408..202101b 100644
--- a/get_file.go
+++ b/get_file.go
@@ -2,6 +2,7 @@ package telegram
 
 import json "github.com/pquerna/ffjson/ffjson"
 
+// GetFileParameters represents data for GetFile method.
 type GetFileParameters struct {
 	FileID string `json:"file_id"`
 }
diff --git a/get_game_high_scores.go b/get_game_high_scores.go
index b5ce0a0..44e2b35 100644
--- a/get_game_high_scores.go
+++ b/get_game_high_scores.go
@@ -2,6 +2,7 @@ package telegram
 
 import json "github.com/pquerna/ffjson/ffjson"
 
+// GetGameHighScoresParameters represents data for GetGameHighScores method.
 type GetGameHighScoresParameters struct {
 	// Target user id
 	UserID int `json:"user_id"`
@@ -19,6 +20,7 @@ type GetGameHighScoresParameters struct {
 	InlineMessageID string `json:"inline_message_id,omitempty"`
 }
 
+// NewGameHighScores creates GetGameHighScoresParameters only with required parameters.
 func NewGameHighScores(userID int) *GetGameHighScoresParameters {
 	return &GetGameHighScoresParameters{
 		UserID: userID,
diff --git a/get_sticker_set.go b/get_sticker_set.go
index 349c78e..654b0da 100644
--- a/get_sticker_set.go
+++ b/get_sticker_set.go
@@ -2,6 +2,7 @@ package telegram
 
 import json "github.com/pquerna/ffjson/ffjson"
 
+// GetStickerSetParameters represents data for GetStickerSet method.
 type GetStickerSetParameters struct {
 	Name string `json:"name"`
 }
diff --git a/get_updates.go b/get_updates.go
index 3d96062..0086381 100644
--- a/get_updates.go
+++ b/get_updates.go
@@ -2,6 +2,7 @@ package telegram
 
 import json "github.com/pquerna/ffjson/ffjson"
 
+// GetUpdatesParameters represents data for GetUpdates method.
 type GetUpdatesParameters struct {
 	// Identifier of the first update to be returned. Must be greater by one than
 	// the highest among the identifiers of previously received updates. By
diff --git a/get_user_profile_photos.go b/get_user_profile_photos.go
index 7fe1a8d..61d25d7 100644
--- a/get_user_profile_photos.go
+++ b/get_user_profile_photos.go
@@ -2,6 +2,7 @@ package telegram
 
 import json "github.com/pquerna/ffjson/ffjson"
 
+// GetUserProfilePhotosParameters represents data for GetUserProfilePhotos method.
 type GetUserProfilePhotosParameters struct {
 	UserID int `json:"user_id"`
 	Offset int `json:"offset"`
diff --git a/kick_chat_member.go b/kick_chat_member.go
index 8ace526..5052ec6 100644
--- a/kick_chat_member.go
+++ b/kick_chat_member.go
@@ -2,6 +2,7 @@ package telegram
 
 import json "github.com/pquerna/ffjson/ffjson"
 
+// KickChatMemberParameters represents data for KickChatMember method.
 type KickChatMemberParameters struct {
 	// Unique identifier for the target chat
 	ChatID int64 `json:"chat_id"`
diff --git a/leave_chat.go b/leave_chat.go
index 4eaba35..81d55e2 100644
--- a/leave_chat.go
+++ b/leave_chat.go
@@ -2,6 +2,7 @@ package telegram
 
 import json "github.com/pquerna/ffjson/ffjson"
 
+// LeaveChatParameters represents data for LeaveChat method.
 type LeaveChatParameters struct {
 	// Unique identifier for the target chat
 	ChatID int64 `json:"chat_id"`
diff --git a/login/check_authorization.go b/login/check_authorization.go
index 6efc220..1e492de 100644
--- a/login/check_authorization.go
+++ b/login/check_authorization.go
@@ -9,6 +9,7 @@ import (
 	"strconv"
 )
 
+// ErrUserNotDefined describes error of an unassigned structure of user
 var ErrUserNotDefined = errors.New("user is not defined")
 
 // CheckAuthorization verify the authentication and the integrity of the data
diff --git a/login/constants.go b/login/constants.go
index 9e8d796..bed2879 100644
--- a/login/constants.go
+++ b/login/constants.go
@@ -1,5 +1,6 @@
 package login
 
+// Key... represents available and supported data keys
 const (
 	KeyAuthDate  = "auth_date"
 	KeyFirstName = "first_name"
diff --git a/pin_chat_message.go b/pin_chat_message.go
index 2283584..928e60f 100644
--- a/pin_chat_message.go
+++ b/pin_chat_message.go
@@ -2,6 +2,7 @@ package telegram
 
 import json "github.com/pquerna/ffjson/ffjson"
 
+// PinChatMessageParameters represents data for PinChatMessage method.
 type PinChatMessageParameters struct {
 	// Unique identifier for the target chat
 	ChatID int64 `json:"chat_id"`
diff --git a/request.go b/request.go
index 5db5d90..ba8cc1e 100644
--- a/request.go
+++ b/request.go
@@ -3,7 +3,6 @@ package telegram
 import (
 	"errors"
 	"fmt"
-	"net/url"
 
 	log "github.com/kirillDanshin/dlog"
 	json "github.com/pquerna/ffjson/ffjson"
@@ -11,18 +10,18 @@ import (
 )
 
 func (bot *Bot) request(dst []byte, method string) (*Response, error) {
-	requestURI := &url.URL{
-		Scheme: "https",
-		Host:   "api.telegram.org",
-		Path:   fmt.Sprint("/bot", bot.AccessToken, "/", method),
-	}
+	requestURI := defaultURI
+	requestURI.Path = fmt.Sprint("/bot", bot.AccessToken, "/", method)
 
 	req := http.AcquireRequest()
 	defer http.ReleaseRequest(req)
 	req.Header.SetContentType("application/json; charset=utf-8")
 	req.Header.SetMethod("POST")
+	if dst == nil {
+		req.Header.SetMethod("GET")
+	}
 	req.Header.SetRequestURI(requestURI.String())
-	req.Header.SetUserAgent("go-telegram/3.5")
+	req.Header.SetUserAgent(fmt.Sprint("telegram/", Version))
 	req.Header.SetHost(requestURI.Hostname())
 	req.SetBody(dst)
 
diff --git a/send_chat_action.go b/send_chat_action.go
index 985615a..d332d84 100644
--- a/send_chat_action.go
+++ b/send_chat_action.go
@@ -2,6 +2,7 @@ package telegram
 
 import json "github.com/pquerna/ffjson/ffjson"
 
+// SendChatActionParameters represents data for SendChatAction method.
 type SendChatActionParameters struct {
 	// Unique identifier for the target chat
 	ChatID int64 `json:"chat_id"`
diff --git a/send_contact.go b/send_contact.go
index b917f7b..979740e 100644
--- a/send_contact.go
+++ b/send_contact.go
@@ -2,6 +2,7 @@ package telegram
 
 import json "github.com/pquerna/ffjson/ffjson"
 
+// SendContactParameters represents data for SendContact method.
 type SendContactParameters struct {
 	// Unique identifier for the target private chat
 	ChatID int64 `json:"chat_id"`
@@ -28,6 +29,7 @@ type SendContactParameters struct {
 	ReplyMarkup *InlineKeyboardMarkup `json:"reply_markup,omitempty"`
 }
 
+// NewContact creates SendContactParameters only with required parameters.
 func NewContact(chatID int64, phoneNumber, firstName string) *SendContactParameters {
 	return &SendContactParameters{
 		ChatID:      chatID,
diff --git a/send_document.go b/send_document.go
index 0ff2d60..9772ce1 100644
--- a/send_document.go
+++ b/send_document.go
@@ -7,6 +7,7 @@ import (
 	http "github.com/valyala/fasthttp"
 )
 
+// SendDocumentParameters represents data for SendDocument method.
 type SendDocumentParameters struct {
 	// Unique identifier for the target chat
 	ChatID int64 `json:"chat_id"`
@@ -34,6 +35,7 @@ type SendDocumentParameters struct {
 	ReplyMarkup interface{} `json:"reply_markup,omitempty"`
 }
 
+// NewDocument creates SendDocumentParameters only with required parameters.
 func NewDocument(chatID int64, document interface{}) *SendDocumentParameters {
 	return &SendDocumentParameters{
 		ChatID:   chatID,
diff --git a/send_game.go b/send_game.go
index beaedb0..efe11a8 100644
--- a/send_game.go
+++ b/send_game.go
@@ -2,6 +2,7 @@ package telegram
 
 import json "github.com/pquerna/ffjson/ffjson"
 
+// SendGameParameters represents data for SendGame method.
 type SendGameParameters struct {
 	// Unique identifier for the target chat
 	ChatID int64 `json:"chat_id"`
@@ -23,6 +24,7 @@ type SendGameParameters struct {
 	ReplyMarkup *InlineKeyboardMarkup `json:"reply_markup,omitempty"`
 }
 
+// NewGame creates SendGameParameters only with required parameters.
 func NewGame(chatID int64, gameShortName string) *SendGameParameters {
 	return &SendGameParameters{
 		ChatID:        chatID,
diff --git a/send_invoice.go b/send_invoice.go
index 6b930e7..39d5f85 100644
--- a/send_invoice.go
+++ b/send_invoice.go
@@ -2,6 +2,7 @@ package telegram
 
 import json "github.com/pquerna/ffjson/ffjson"
 
+// SendInvoiceParameters represents data for SendInvoice method.
 type SendInvoiceParameters struct {
 	// Unique identifier for the target private chat
 	ChatID int64 `json:"chat_id"`
@@ -78,6 +79,7 @@ type SendInvoiceParameters struct {
 	ReplyMarkup *InlineKeyboardMarkup `json:"reply_markup,omitempty"`
 }
 
+// NewInvoice creates SendInvoiceParameters only with required parameters.
 func NewInvoice(chatID int64, title, description, payload, providerToken, startParameter, currency string, prices ...LabeledPrice) *SendInvoiceParameters {
 	return &SendInvoiceParameters{
 		ChatID:         chatID,
diff --git a/send_location.go b/send_location.go
index 3638f96..ca5c36b 100644
--- a/send_location.go
+++ b/send_location.go
@@ -2,6 +2,7 @@ package telegram
 
 import json "github.com/pquerna/ffjson/ffjson"
 
+// SendLocationParameters represents data for SendLocation method.
 type SendLocationParameters struct {
 	// Unique identifier for the target private chat
 	ChatID int64 `json:"chat_id"`
@@ -29,6 +30,7 @@ type SendLocationParameters struct {
 	ReplyMarkup *InlineKeyboardMarkup `json:"reply_markup,omitempty"`
 }
 
+// NewLocation creates SendLocationParameters only with required parameters.
 func NewLocation(chatID int64, latitude, longitude float32) *SendLocationParameters {
 	return &SendLocationParameters{
 		ChatID:    chatID,
diff --git a/send_media_group.go b/send_media_group.go
index 846b6ea..b026064 100644
--- a/send_media_group.go
+++ b/send_media_group.go
@@ -2,6 +2,7 @@ package telegram
 
 import json "github.com/pquerna/ffjson/ffjson"
 
+// SendMediaGroupParameters represents data for SendMediaGroup method.
 type SendMediaGroupParameters struct {
 	// Unique identifier for the target chat.
 	ChatID int64 `json:"chat_id"`
@@ -18,6 +19,7 @@ type SendMediaGroupParameters struct {
 	ReplyToMessageID int `json:"reply_to_message_id,omitempty"`
 }
 
+// NewMediaGroup creates SendMediaGroupParameters only with required parameters.
 func NewMediaGroup(chatID int64, media ...interface{}) *SendMediaGroupParameters {
 	return &SendMediaGroupParameters{
 		ChatID: chatID,
diff --git a/send_message.go b/send_message.go
index 58677f7..8347c27 100644
--- a/send_message.go
+++ b/send_message.go
@@ -2,6 +2,7 @@ package telegram
 
 import json "github.com/pquerna/ffjson/ffjson"
 
+// SendMessageParameters represents data for SendMessage method.
 type SendMessageParameters struct {
 	// Unique identifier for the target chat or username of the target channel
 	// (in the format @channelusername)
@@ -30,6 +31,7 @@ type SendMessageParameters struct {
 	ReplyMarkup interface{} `json:"reply_markup,omitempty"`
 }
 
+// NewMessage creates SendMessageParameters only with required parameters.
 func NewMessage(chatID int64, text string) *SendMessageParameters {
 	return &SendMessageParameters{
 		ChatID: chatID,
diff --git a/send_photo.go b/send_photo.go
index 9992131..6d0de3c 100644
--- a/send_photo.go
+++ b/send_photo.go
@@ -7,6 +7,7 @@ import (
 	http "github.com/valyala/fasthttp"
 )
 
+// SendPhotoParameters represents data for SendPhoto method.
 type SendPhotoParameters struct {
 	// Unique identifier for the target chat
 	ChatID int64 `json:"chat_id"`
@@ -41,6 +42,7 @@ type SendPhotoParameters struct {
 	ReplyMarkup interface{} `json:"reply_markup,omitempty"`
 }
 
+// NewPhoto creates SendPhotoParameters only with required parameters.
 func NewPhoto(chatID int64, photo interface{}) *SendPhotoParameters {
 	return &SendPhotoParameters{
 		ChatID: chatID,
diff --git a/send_venue.go b/send_venue.go
index 8273736..6508f29 100644
--- a/send_venue.go
+++ b/send_venue.go
@@ -2,6 +2,7 @@ package telegram
 
 import json "github.com/pquerna/ffjson/ffjson"
 
+// SendVenueParameters represents data for SendVenue method.
 type SendVenueParameters struct {
 	// Unique identifier for the target private chat
 	ChatID int64 `json:"chat_id"`
@@ -34,6 +35,7 @@ type SendVenueParameters struct {
 	ReplyMarkup *InlineKeyboardMarkup `json:"reply_markup,omitempty"`
 }
 
+// NewVenue creates SendVenueParameters only with required parameters.
 func NewVenue(chatID int64, latitude, longitude float32, title, address string) *SendVenueParameters {
 	return &SendVenueParameters{
 		ChatID:    chatID,
diff --git a/set_chat_description.go b/set_chat_description.go
index 5e938d4..6968a96 100644
--- a/set_chat_description.go
+++ b/set_chat_description.go
@@ -2,6 +2,7 @@ package telegram
 
 import json "github.com/pquerna/ffjson/ffjson"
 
+// SetChatDescriptionParameters represents data for SetChatDescription method.
 type SetChatDescriptionParameters struct {
 	// Unique identifier for the target chat
 	ChatID int64 `json:"chat_id"`
diff --git a/set_chat_photo.go b/set_chat_photo.go
index c98e341..cc7d3aa 100644
--- a/set_chat_photo.go
+++ b/set_chat_photo.go
@@ -7,6 +7,7 @@ import (
 	http "github.com/valyala/fasthttp"
 )
 
+// SetChatPhotoParameters represents data for SetChatPhoto method.
 type SetChatPhotoParameters struct {
 	// Unique identifier for the target chat
 	ChatID int64 `json:"chat_id"`
diff --git a/set_chat_sticker_set.go b/set_chat_sticker_set.go
index cb08b7a..61e3d26 100644
--- a/set_chat_sticker_set.go
+++ b/set_chat_sticker_set.go
@@ -2,6 +2,7 @@ package telegram
 
 import json "github.com/pquerna/ffjson/ffjson"
 
+// SetChatStickerSetParameters represents data for SetChatStickerSet method.
 type SetChatStickerSetParameters struct {
 	// Unique identifier for the target chat
 	ChatID int64 `json:"chat_id"`
diff --git a/set_chat_title.go b/set_chat_title.go
index 7b75d34..e6a25a8 100644
--- a/set_chat_title.go
+++ b/set_chat_title.go
@@ -2,6 +2,7 @@ package telegram
 
 import json "github.com/pquerna/ffjson/ffjson"
 
+// SetChatTitleParameters represents data for SetChatTitle method.
 type SetChatTitleParameters struct {
 	// Unique identifier for the target chat
 	ChatID int64 `json:"chat_id"`
diff --git a/set_game_score.go b/set_game_score.go
index 25ae59e..9dd30a5 100644
--- a/set_game_score.go
+++ b/set_game_score.go
@@ -2,6 +2,7 @@ package telegram
 
 import json "github.com/pquerna/ffjson/ffjson"
 
+// SetGameScoreParameters represents data for SetGameScore method.
 type SetGameScoreParameters struct {
 	// User identifier
 	UserID int `json:"user_id"`
@@ -30,6 +31,7 @@ type SetGameScoreParameters struct {
 	InlineMessageID string `json:"inline_message_id,omitempty"`
 }
 
+// NewGameScore creates SetGameScoreParameters only with required parameters.
 func NewGameScore(userID, score int) *SetGameScoreParameters {
 	return &SetGameScoreParameters{
 		UserID: userID,
diff --git a/set_sticker_position_in_set.go b/set_sticker_position_in_set.go
index f466004..37f0f48 100644
--- a/set_sticker_position_in_set.go
+++ b/set_sticker_position_in_set.go
@@ -2,6 +2,8 @@ package telegram
 
 import json "github.com/pquerna/ffjson/ffjson"
 
+// SetStickerPositionInSetParameters represents data for SetStickerPositionInSet
+// method.
 type SetStickerPositionInSetParameters struct {
 	Sticker  string `json:"sticker"`
 	Position int    `json:"position"`
diff --git a/set_webhook.go b/set_webhook.go
index d912613..e090266 100644
--- a/set_webhook.go
+++ b/set_webhook.go
@@ -8,6 +8,7 @@ import (
 	http "github.com/valyala/fasthttp"
 )
 
+// SetWebhookParameters represents data for SetWebhook method.
 type SetWebhookParameters struct {
 	// HTTPS url to send updates to. Use an empty string to remove webhook
 	// integration
@@ -36,6 +37,7 @@ type SetWebhookParameters struct {
 	AllowedUpdates []string `json:"allowed_updates,omitempty"`
 }
 
+// NewWebhook creates new SetWebhookParameters only with required parameters.
 func NewWebhook(url string, file interface{}) *SetWebhookParameters {
 	return &SetWebhookParameters{
 		URL:         url,
diff --git a/unban_chat_member.go b/unban_chat_member.go
index 52d6a85..61553b7 100644
--- a/unban_chat_member.go
+++ b/unban_chat_member.go
@@ -2,6 +2,7 @@ package telegram
 
 import json "github.com/pquerna/ffjson/ffjson"
 
+// UnbanChatMemberParameters represents data for UnbanChatMember method.
 type UnbanChatMemberParameters struct {
 	// Unique identifier for the target chat
 	ChatID int64 `json:"chat_id"`
diff --git a/unpin_chat_message.go b/unpin_chat_message.go
index a59398f..15e6fa1 100644
--- a/unpin_chat_message.go
+++ b/unpin_chat_message.go
@@ -2,6 +2,7 @@ package telegram
 
 import json "github.com/pquerna/ffjson/ffjson"
 
+// UnpinChatMessageParameters represents data for UnpinChatMessage method.
 type UnpinChatMessageParameters struct {
 	// Unique identifier for the target chat
 	ChatID int64 `json:"chat_id"`
diff --git a/upload.go b/upload.go
index 2dd54c8..388d608 100644
--- a/upload.go
+++ b/upload.go
@@ -14,6 +14,7 @@ import (
 	http "github.com/valyala/fasthttp"
 )
 
+// ErrBadFileType describes error of the unsupported file data type for uploading
 var ErrBadFileType = errors.New("bad file type")
 
 /*
@@ -23,8 +24,10 @@ media, etc.):
 1. If the file is already stored somewhere on the Telegram servers, you don't need to reupload it:
 each file object has a file_id field, simply pass this file_id as a parameter instead of uploading.
 There are no limits for files sent this way.
+
 2. Provide Telegram with an *url.URL for the file to be sent. Telegram will download and send the
 file. 5 MB max size for photos and 20 MB max for other types of content.
+
 3. Post the file using multipart/form-data in the usual way that files are uploaded via the
 browser. Use []byte or io.Reader for this. 10 MB max size for photos, 50 MB for other files.
 
@@ -49,11 +52,8 @@ func (bot *Bot) Upload(method, key, name string, file InputFile, args fmt.String
 	buffer := bytes.NewBuffer(nil)
 	multi := multipart.NewWriter(buffer)
 
-	requestURI := &url.URL{
-		Scheme: "https",
-		Host:   "api.telegram.org",
-		Path:   fmt.Sprint("/bot", bot.AccessToken, "/", method),
-	}
+	requestURI := defaultURI
+	requestURI.Path = fmt.Sprint("/bot", bot.AccessToken, "/", method)
 
 	query, err := url.ParseQuery(args.String())
 	if err != nil {
@@ -66,19 +66,7 @@ func (bot *Bot) Upload(method, key, name string, file InputFile, args fmt.String
 		}
 	}
 
-	switch src := file.(type) {
-	case string:
-		err = uploadByString(multi, key, src)
-	case *url.URL: // Send by URL
-		err = uploadFromURL(multi, key, src)
-	case []byte: // Upload new
-		err = uploadFromMemory(multi, key, name, bytes.NewReader(src))
-	case io.Reader: // Upload new
-		err = uploadFromMemory(multi, key, name, src)
-	default:
-		return nil, ErrBadFileType
-	}
-	if err != nil {
+	if err = createFileField(multi, file, key, name); err != nil {
 		return nil, err
 	}
 
@@ -92,23 +80,21 @@ func (bot *Bot) Upload(method, key, name string, file InputFile, args fmt.String
 	req.Header.SetContentType(multi.FormDataContentType())
 	req.Header.SetMethod("POST")
 	req.Header.SetRequestURI(requestURI.String())
-	req.Header.SetUserAgent("go-telegram/3.5")
-	req.Header.SetHost("api.telegram.org")
+	req.Header.SetUserAgent(fmt.Sprint("telegram/", Version))
+	req.Header.SetHost(requestURI.Hostname())
 
 	log.Ln("Request:")
 	log.D(req)
 
 	resp := http.AcquireResponse()
 	defer http.ReleaseResponse(resp)
-	if err = http.Do(req, resp); err != nil {
-		log.Ln("Resp:")
-		log.D(resp)
-
-		return nil, err
-	}
 
+	err = http.Do(req, resp)
 	log.Ln("Resp:")
 	log.D(resp)
+	if err != nil {
+		return nil, err
+	}
 
 	var data Response
 	if err = json.Unmarshal(resp.Body(), &data); err != nil {
@@ -122,19 +108,34 @@ func (bot *Bot) Upload(method, key, name string, file InputFile, args fmt.String
 	return &data, nil
 }
 
-func uploadByString(w *multipart.Writer, key, src string) error {
-	_, err := os.Stat(src)
-	switch {
-	case os.IsNotExist(err):
-		err = uploadFromFileID(w, key, src)
-	case os.IsExist(err):
-		err = uploadFromDisk(w, key, src)
+func createFileField(w *multipart.Writer, file interface{}, key, val string) error {
+	var err error
+	switch src := file.(type) {
+	case string: // Send FileID of file on disk path
+		err = createFileFieldString(w, key, src)
+	case *url.URL: // Send by URL
+		err = w.WriteField(key, src.String())
+	case []byte: // Upload new
+		err = createFileFieldRaw(w, key, val, bytes.NewReader(src))
+	case io.Reader: // Upload new
+		err = createFileFieldRaw(w, key, val, src)
+	default:
+		return ErrBadFileType
 	}
 	return err
 }
 
-func uploadFromFileID(w *multipart.Writer, key, src string) error {
-	return w.WriteField(key, src)
+func createFileFieldString(w *multipart.Writer, key, src string) error {
+	_, err := os.Stat(src)
+
+	switch {
+	case os.IsNotExist(err):
+		err = w.WriteField(key, src)
+	case os.IsExist(err):
+		err = uploadFromDisk(w, key, src)
+	}
+
+	return err
 }
 
 func uploadFromDisk(w *multipart.Writer, key, src string) error {
@@ -156,11 +157,7 @@ func uploadFromDisk(w *multipart.Writer, key, src string) error {
 	return err
 }
 
-func uploadFromURL(w *multipart.Writer, key string, src *url.URL) error {
-	return w.WriteField(key, src.String())
-}
-
-func uploadFromMemory(w *multipart.Writer, key, value string, src io.Reader) error {
+func createFileFieldRaw(w *multipart.Writer, key, value string, src io.Reader) error {
 	field, err := w.CreateFormFile(key, value)
 	if err != nil {
 		return err
diff --git a/utils.go b/utils.go
index 6b27183..e57839b 100644
--- a/utils.go
+++ b/utils.go
@@ -5,10 +5,12 @@ import (
 	"strconv"
 )
 
+// NewForceReply calls the response interface to the message.
 func NewForceReply() *ForceReply {
 	return &ForceReply{ForceReply: true}
 }
 
+// NewInlineMentionURL creates a url.URL for the mention user without username.
 func NewInlineMentionURL(userID int) *url.URL {
 	link := &url.URL{
 		Scheme: SchemeTelegram,
diff --git a/utils_bot.go b/utils_bot.go
index e2de5c2..f9d633e 100644
--- a/utils_bot.go
+++ b/utils_bot.go
@@ -6,61 +6,42 @@ import (
 	"strings"
 )
 
+// Bot represents a bot user with access token getted from @BotFather.
 type Bot struct {
 	AccessToken string
 	*User
 }
 
+// New creates a new Bot structure based on the input access token.
 func New(accessToken string) (*Bot, error) {
 	var err error
-	bot := &Bot{AccessToken: accessToken}
+	bot := new(Bot)
+	bot.AccessToken = accessToken
 
 	bot.User, err = bot.GetMe()
 	return bot, err
 }
 
+// IsMessageFromMe checks that the input message is a message from the current
+// bot.
 func (bot *Bot) IsMessageFromMe(msg *Message) bool {
-	if msg == nil || bot == nil {
-		return false
-	}
-
-	if msg.From == nil || bot.User == nil {
-		return false
-	}
-
-	return msg.From.ID == bot.ID
+	return msg != nil && bot != nil && msg.From != nil && bot.User != nil && msg.From.ID == bot.ID
 }
 
+// IsForwardFromMe checks that the input message is a forwarded message from the
+// current bot.
 func (bot *Bot) IsForwardFromMe(msg *Message) bool {
-	if !msg.IsForward() {
-		return false
-	}
-
-	if bot == nil {
-		return false
-	}
-
-	if bot.User == nil {
-		return false
-	}
-
-	return msg.ForwardFrom.ID == bot.ID
+	return msg.IsForward() && bot != nil && bot.User != nil && msg.ForwardFrom.ID == bot.ID
 }
 
+// IsReplyToMe checks that the input message is a reply to the current bot.
 func (bot *Bot) IsReplyToMe(msg *Message) bool {
-	if msg.Chat.IsPrivate() {
-		return true
-	}
-
-	if !msg.IsReply() {
-		return false
-	}
-
-	return bot.IsMessageFromMe(msg.ReplyToMessage)
+	return msg.Chat.IsPrivate() || (msg.IsReply() && bot.IsMessageFromMe(msg.ReplyToMessage))
 }
 
+// IsCommandToMe checks that the input message is a command for the current bot.
 func (bot *Bot) IsCommandToMe(msg *Message) bool {
-	if !msg.IsCommand("") {
+	if !msg.IsCommand() {
 		return false
 	}
 
@@ -76,12 +57,9 @@ func (bot *Bot) IsCommandToMe(msg *Message) bool {
 	return strings.ToLower(parts[1]) == strings.ToLower(bot.User.Username)
 }
 
+// IsMessageMentionsMe checks that the input message mentions the current bot.
 func (bot *Bot) IsMessageMentionsMe(msg *Message) bool {
-	if msg == nil || bot == nil {
-		return false
-	}
-
-	if bot.User == nil {
+	if msg == nil || bot == nil || bot.User == nil {
 		return false
 	}
 
@@ -108,59 +86,45 @@ func (bot *Bot) IsMessageMentionsMe(msg *Message) bool {
 	return false
 }
 
+// IsForwardMentionsMe checks that the input forwarded message mentions the
+// current bot.
 func (bot *Bot) IsForwardMentionsMe(msg *Message) bool {
 	return msg.IsForward() && bot.IsMessageMentionsMe(msg)
 }
 
+// IsReplyMentionsMe checks that the input message mentions the current bot.
 func (bot *Bot) IsReplyMentionsMe(msg *Message) bool {
 	return msg.IsReply() && bot.IsMessageMentionsMe(msg.ReplyToMessage)
 }
 
+// IsMessageToMe checks that the input message is addressed to the current bot.
 func (bot *Bot) IsMessageToMe(msg *Message) bool {
-	if msg == nil {
+	if msg == nil || msg.Chat == nil {
 		return false
 	}
 
-	if msg.Chat == nil {
-		return false
-	}
-
-	if msg.Chat.IsPrivate() ||
-		bot.IsCommandToMe(msg) ||
-		bot.IsReplyToMe(msg) ||
-		bot.IsMessageMentionsMe(msg) {
+	if msg.Chat.IsPrivate() || bot.IsCommandToMe(msg) || bot.IsReplyToMe(msg) || bot.IsMessageMentionsMe(msg) {
 		return true
 	}
 
 	return false
 }
 
+// NewFileURL creates a url.URL to file with path getted from GetFile method.
 func (bot *Bot) NewFileURL(filePath string) *url.URL {
-	if bot == nil {
+	if bot == nil || bot.AccessToken == "" || filePath == "" {
 		return nil
 	}
 
-	if bot.AccessToken == "" || filePath == "" {
-		return nil
-	}
+	result := defaultURI
+	result.Path = fmt.Sprint("/file/bot", bot.AccessToken, "/", filePath)
 
-	return &url.URL{
-		Scheme: "https",
-		Host:   "api.telegram.org",
-		Path:   fmt.Sprint("/file/bot", bot.AccessToken, "/", filePath),
-	}
+	return result
 }
 
-func (bot *Bot) NewRedirectURL(group bool, param string) *url.URL {
-	if bot == nil {
-		return nil
-	}
-
-	if bot.User == nil {
-		return nil
-	}
-
-	if bot.User.Username == "" {
+// NewRedirectURL creates new url.URL for redirecting from one chat to another.
+func (bot *Bot) NewRedirectURL(param string, group bool) *url.URL {
+	if bot == nil || bot.User == nil || bot.User.Username == "" {
 		return nil
 	}
 
@@ -171,11 +135,11 @@ func (bot *Bot) NewRedirectURL(group bool, param string) *url.URL {
 	}
 
 	q := link.Query()
+	key := "start"
 	if group {
-		q.Add("startgroup", param)
-	} else {
-		q.Add("start", param)
+		key += "group"
 	}
+	q.Add(key, param)
 
 	link.RawQuery = q.Encode()
 
diff --git a/utils_chat.go b/utils_chat.go
index 331137e..d4839fd 100644
--- a/utils_chat.go
+++ b/utils_chat.go
@@ -2,60 +2,39 @@ package telegram
 
 import "fmt"
 
+// IsPrivate checks that the current chat is a private chat with single user.
 func (chat *Chat) IsPrivate() bool {
-	if chat == nil {
-		return false
-	}
-
-	return chat.Type == ChatPrivate
+	return chat != nil && chat.Type == ChatPrivate
 }
 
+// IsGroup checks that the current chat is a group.
 func (chat *Chat) IsGroup() bool {
-	if chat == nil {
-		return false
-	}
-
-	return chat.Type == ChatGroup
+	return chat != nil && chat.Type == ChatGroup
 }
 
+// IsSuperGroup checks that the current chat is a supergroup.
 func (chat *Chat) IsSuperGroup() bool {
-	if chat == nil {
-		return false
-	}
-
-	return chat.Type == ChatSuperGroup
+	return chat != nil && chat.Type == ChatSuperGroup
 }
 
+// IsChannel checks that the current chat is a channel.
 func (chat *Chat) IsChannel() bool {
-	if chat == nil {
-		return false
-	}
-
-	return chat.Type == ChatChannel
+	return chat != nil && chat.Type == ChatChannel
 }
 
+// HasPinnedMessage checks that the current chat has a pinned message.
 func (chat *Chat) HasPinnedMessage() bool {
-	if chat == nil {
-		return false
-	}
-
-	return chat.PinnedMessage != nil
+	return chat != nil && chat.PinnedMessage != nil
 }
 
+// HasStickerSet checks that the current chat has a sticker set.
 func (chat *Chat) HasStickerSet() bool {
-	if chat == nil {
-		return false
-	}
-
-	return chat.StickerSetName != ""
+	return chat != nil && chat.StickerSetName != ""
 }
 
+// StickerSet return StickerSet structure if StickerSetName is available.
 func (chat *Chat) StickerSet(bot *Bot) *StickerSet {
-	if !chat.HasStickerSet() {
-		return nil
-	}
-
-	if bot == nil {
+	if !chat.HasStickerSet() || bot == nil {
 		return nil
 	}
 
@@ -67,6 +46,7 @@ func (chat *Chat) StickerSet(bot *Bot) *StickerSet {
 	return set
 }
 
+// FullName returns the full name of chat or FirstName if LastName is not available.
 func (chat *Chat) FullName() string {
 	if chat == nil {
 		return ""
diff --git a/utils_entity.go b/utils_entity.go
index d13516f..5e027d0 100644
--- a/utils_entity.go
+++ b/utils_entity.go
@@ -5,16 +5,9 @@ import (
 	"net/url"
 )
 
+// ParseURL selects URL from entered text of message and parse it as url.URL.
 func (entity *MessageEntity) ParseURL(messageText string) *url.URL {
-	if entity == nil {
-		return nil
-	}
-
-	if !entity.IsURL() {
-		return nil
-	}
-
-	if messageText == "" {
+	if entity == nil || !entity.IsURL() || messageText == "" {
 		return nil
 	}
 
@@ -36,94 +29,62 @@ func (entity *MessageEntity) ParseURL(messageText string) *url.URL {
 	return link
 }
 
+// IsBold checks that the current entity is a bold tag.
 func (entity *MessageEntity) IsBold() bool {
-	if entity == nil {
-		return false
-	}
-
-	return entity.Type == EntityBold
+	return entity != nil && entity.Type == EntityBold
 }
 
+// IsBotCommand checks that the current entity is a bot command.
 func (entity *MessageEntity) IsBotCommand() bool {
-	if entity == nil {
-		return false
-	}
-
-	return entity.Type == EntityBotCommand
+	return entity != nil && entity.Type == EntityBotCommand
 }
 
+// IsCode checks that the current entity is a code tag.
 func (entity *MessageEntity) IsCode() bool {
-	if entity == nil {
-		return false
-	}
-
-	return entity.Type == EntityCode
+	return entity != nil && entity.Type == EntityCode
 }
 
+// IsEmail checks that the current entity is a email.
 func (entity *MessageEntity) IsEmail() bool {
-	if entity == nil {
-		return false
-	}
-
-	return entity.Type == EntityEmail
+	return entity != nil && entity.Type == EntityEmail
 }
 
+// IsHashtag checks that the current entity is a hashtag.
 func (entity *MessageEntity) IsHashtag() bool {
-	if entity == nil {
-		return false
-	}
-
-	return entity.Type == EntityHashtag
+	return entity != nil && entity.Type == EntityHashtag
 }
 
+// IsItalic checks that the current entity is a italic tag.
 func (entity *MessageEntity) IsItalic() bool {
-	if entity == nil {
-		return false
-	}
-
-	return entity.Type == EntityItalic
+	return entity != nil && entity.Type == EntityItalic
 }
 
+// IsMention checks that the current entity is a username mention.
 func (entity *MessageEntity) IsMention() bool {
-	if entity == nil {
-		return false
-	}
-
-	return entity.Type == EntityMention
+	return entity != nil && entity.Type == EntityMention
 }
 
+// IsPre checks that the current entity is a pre tag.
 func (entity *MessageEntity) IsPre() bool {
-	if entity == nil {
-		return false
-	}
-
-	return entity.Type == EntityPre
+	return entity != nil && entity.Type == EntityPre
 }
 
+// IsTextLink checks that the current entity is a text link.
 func (entity *MessageEntity) IsTextLink() bool {
-	if entity == nil {
-		return false
-	}
-
-	return entity.Type == EntityTextLink
+	return entity != nil && entity.Type == EntityTextLink
 }
 
+// IsTextMention checks that the current entity is a mention without username.
 func (entity *MessageEntity) IsTextMention() bool {
-	if entity == nil {
-		return false
-	}
-
-	return entity.Type == EntityTextMention
+	return entity != nil && entity.Type == EntityTextMention
 }
 
+// IsURL checks that the current entity is a URL
 func (entity *MessageEntity) IsURL() bool {
-	if entity == nil {
-		return false
-	}
-
-	return entity.Type == EntityURL
+	return entity != nil && entity.Type == EntityURL
 }
 
+// TextLink parse current text link entity as url.URL.
 func (entity *MessageEntity) TextLink() *url.URL {
 	if entity == nil {
 		return nil
diff --git a/utils_inline_keyboard.go b/utils_inline_keyboard.go
index 62301f9..345a3ff 100644
--- a/utils_inline_keyboard.go
+++ b/utils_inline_keyboard.go
@@ -1,5 +1,6 @@
 package telegram
 
+// NewInlineKeyboardMarkup creates a new inline keyboard markup for message.
 func NewInlineKeyboardMarkup(rows ...[]InlineKeyboardButton) *InlineKeyboardMarkup {
 	var keyboard [][]InlineKeyboardButton
 	keyboard = append(keyboard, rows...)
@@ -8,12 +9,14 @@ func NewInlineKeyboardMarkup(rows ...[]InlineKeyboardButton) *InlineKeyboardMark
 	}
 }
 
+// NewInlineKeyboardRow creates a new inline keyboard row for buttons.
 func NewInlineKeyboardRow(buttons ...InlineKeyboardButton) []InlineKeyboardButton {
 	var row []InlineKeyboardButton
 	row = append(row, buttons...)
 	return row
 }
 
+// NewInlineKeyboardButton creates a new inline keyboard callback button.
 func NewInlineKeyboardButton(text, data string) InlineKeyboardButton {
 	return InlineKeyboardButton{
 		Text:         text,
@@ -21,6 +24,7 @@ func NewInlineKeyboardButton(text, data string) InlineKeyboardButton {
 	}
 }
 
+// NewInlineKeyboardButtonURL creates a new inline keyboard button with URL.
 func NewInlineKeyboardButtonURL(text, url string) InlineKeyboardButton {
 	return InlineKeyboardButton{
 		Text: text,
@@ -28,6 +32,8 @@ func NewInlineKeyboardButtonURL(text, url string) InlineKeyboardButton {
 	}
 }
 
+// NewInlineKeyboardButtonSwitch creates a new inline keyboard button to make
+// specific inline query in other chat.
 func NewInlineKeyboardButtonSwitch(text, query string) InlineKeyboardButton {
 	return InlineKeyboardButton{
 		Text:              text,
@@ -35,6 +41,8 @@ func NewInlineKeyboardButtonSwitch(text, query string) InlineKeyboardButton {
 	}
 }
 
+// NewInlineKeyboardButtonSwitchSelf creates a new inline keyboard button to make
+// specific inline query in same chat.
 func NewInlineKeyboardButtonSwitchSelf(text, query string) InlineKeyboardButton {
 	return InlineKeyboardButton{
 		Text: text,
@@ -42,6 +50,8 @@ func NewInlineKeyboardButtonSwitchSelf(text, query string) InlineKeyboardButton
 	}
 }
 
+// NewInlineKeyboardButtonGame creates a new inline keyboard button with game
+// callback.
 func NewInlineKeyboardButtonGame(text string) InlineKeyboardButton {
 	var game CallbackGame
 	return InlineKeyboardButton{
@@ -50,6 +60,8 @@ func NewInlineKeyboardButtonGame(text string) InlineKeyboardButton {
 	}
 }
 
+// NewInlineKeyboardButtonPay creates a new inline keyboard button with pay
+// callback.
 func NewInlineKeyboardButtonPay(text string) InlineKeyboardButton {
 	return InlineKeyboardButton{
 		Text: text,
diff --git a/utils_inline_query_result.go b/utils_inline_query_result.go
index 067e710..b6af143 100644
--- a/utils_inline_query_result.go
+++ b/utils_inline_query_result.go
@@ -1,5 +1,7 @@
 package telegram
 
+// NewInlineQueryResultCachedAudio creates a new inline query result with cached
+// audio.
 func NewInlineQueryResultCachedAudio(resultID, fileID string) *InlineQueryResultCachedAudio {
 	return &InlineQueryResultCachedAudio{
 		Type:        TypeAudio,
@@ -8,6 +10,8 @@ func NewInlineQueryResultCachedAudio(resultID, fileID string) *InlineQueryResult
 	}
 }
 
+// NewInlineQueryResultCachedDocument creates a new inline query result with
+// cached document.
 func NewInlineQueryResultCachedDocument(resultID, fileID, title string) *InlineQueryResultCachedDocument {
 	return &InlineQueryResultCachedDocument{
 		Type:           TypeDocument,
@@ -17,6 +21,8 @@ func NewInlineQueryResultCachedDocument(resultID, fileID, title string) *InlineQ
 	}
 }
 
+// NewInlineQueryResultCachedGif creates a new inline query result with cached
+// GIF.
 func NewInlineQueryResultCachedGif(resultID, fileID string) *InlineQueryResultCachedGif {
 	return &InlineQueryResultCachedGif{
 		Type:      TypeGIF,
@@ -25,6 +31,8 @@ func NewInlineQueryResultCachedGif(resultID, fileID string) *InlineQueryResultCa
 	}
 }
 
+// NewInlineQueryResultCachedMpeg4Gif creates a new inline query result with
+// cached MPEG GIF.
 func NewInlineQueryResultCachedMpeg4Gif(resultID, fileID string) *InlineQueryResultCachedMpeg4Gif {
 	return &InlineQueryResultCachedMpeg4Gif{
 		Type:        TypeMpeg4Gif,
@@ -33,6 +41,8 @@ func NewInlineQueryResultCachedMpeg4Gif(resultID, fileID string) *InlineQueryRes
 	}
 }
 
+// NewInlineQueryResultCachedPhoto creates a new inline query result with cached
+// photo.
 func NewInlineQueryResultCachedPhoto(resultID, fileID string) *InlineQueryResultCachedPhoto {
 	return &InlineQueryResultCachedPhoto{
 		Type:        TypePhoto,
@@ -41,6 +51,8 @@ func NewInlineQueryResultCachedPhoto(resultID, fileID string) *InlineQueryResult
 	}
 }
 
+// NewInlineQueryResultCachedSticker creates a new inline query result with
+// cached sticker.
 func NewInlineQueryResultCachedSticker(resultID, fileID string) *InlineQueryResultCachedSticker {
 	return &InlineQueryResultCachedSticker{
 		Type:          TypeSticker,
@@ -49,6 +61,8 @@ func NewInlineQueryResultCachedSticker(resultID, fileID string) *InlineQueryResu
 	}
 }
 
+// NewInlineQueryResultCachedVideo creates a new inline query result with cached
+// video.
 func NewInlineQueryResultCachedVideo(resultID, fileID, title string) *InlineQueryResultCachedVideo {
 	return &InlineQueryResultCachedVideo{
 		Type:        TypeVideo,
@@ -58,6 +72,8 @@ func NewInlineQueryResultCachedVideo(resultID, fileID, title string) *InlineQuer
 	}
 }
 
+// NewInlineQueryResultCachedVoice creates a new inline query result with cached
+// voice.
 func NewInlineQueryResultCachedVoice(resultID, fileID, title string) *InlineQueryResultCachedVoice {
 	return &InlineQueryResultCachedVoice{
 		Type:        TypeVoice,
@@ -67,6 +83,7 @@ func NewInlineQueryResultCachedVoice(resultID, fileID, title string) *InlineQuer
 	}
 }
 
+// NewInlineQueryResultArticle creates a new inline query result with article.
 func NewInlineQueryResultArticle(resultID, title string, content *InputMessageContent) *InlineQueryResultArticle {
 	return &InlineQueryResultArticle{
 		Type:                TypeArticle,
@@ -76,6 +93,7 @@ func NewInlineQueryResultArticle(resultID, title string, content *InputMessageCo
 	}
 }
 
+// NewInlineQueryResultAudio creates a new inline query result with audio.
 func NewInlineQueryResultAudio(resultID, audioURL, title string) *InlineQueryResultAudio {
 	return &InlineQueryResultAudio{
 		Type:     TypeAudio,
@@ -85,6 +103,7 @@ func NewInlineQueryResultAudio(resultID, audioURL, title string) *InlineQueryRes
 	}
 }
 
+// NewInlineQueryResultContact creates a new inline query result with contact.
 func NewInlineQueryResultContact(resultID, phoneNumber, firstName string) *InlineQueryResultContact {
 	return &InlineQueryResultContact{
 		Type:        TypeContact,
@@ -94,6 +113,7 @@ func NewInlineQueryResultContact(resultID, phoneNumber, firstName string) *Inlin
 	}
 }
 
+// NewInlineQueryResultGame creates a new inline query result with game.
 func NewInlineQueryResultGame(resultID, gameShortName string) *InlineQueryResultGame {
 	return &InlineQueryResultGame{
 		Type:          TypeGame,
@@ -102,6 +122,7 @@ func NewInlineQueryResultGame(resultID, gameShortName string) *InlineQueryResult
 	}
 }
 
+// NewInlineQueryResultDocument creates a new inline query result with document.
 func NewInlineQueryResultDocument(resultID, title, documentURL, mimeType string) *InlineQueryResultDocument {
 	return &InlineQueryResultDocument{
 		Type:        TypeDocument,
@@ -112,6 +133,7 @@ func NewInlineQueryResultDocument(resultID, title, documentURL, mimeType string)
 	}
 }
 
+// NewInlineQueryResultGif creates a new inline query result with GIF.
 func NewInlineQueryResultGif(resultID, gifURL, thumbURL string) *InlineQueryResultGif {
 	return &InlineQueryResultGif{
 		Type:     TypeGIF,
@@ -121,6 +143,7 @@ func NewInlineQueryResultGif(resultID, gifURL, thumbURL string) *InlineQueryResu
 	}
 }
 
+// NewInlineQueryResultLocation creates a new inline query result with location.
 func NewInlineQueryResultLocation(resultID, title string, latitude, longitude float32) *InlineQueryResultLocation {
 	return &InlineQueryResultLocation{
 		Type:      TypeLocation,
@@ -131,6 +154,7 @@ func NewInlineQueryResultLocation(resultID, title string, latitude, longitude fl
 	}
 }
 
+// NewInlineQueryResultMpeg4Gif creates a new inline query result with MPEG GIF.
 func NewInlineQueryResultMpeg4Gif(resultID, mpeg4URL, thumbURL string) *InlineQueryResultMpeg4Gif {
 	return &InlineQueryResultMpeg4Gif{
 		Type:     TypeMpeg4Gif,
@@ -140,6 +164,7 @@ func NewInlineQueryResultMpeg4Gif(resultID, mpeg4URL, thumbURL string) *InlineQu
 	}
 }
 
+// NewInlineQueryResultPhoto creates a new inline query result with photo.
 func NewInlineQueryResultPhoto(resultID, photoURL, thumbURL string) *InlineQueryResultPhoto {
 	return &InlineQueryResultPhoto{
 		Type:     TypePhoto,
@@ -149,6 +174,7 @@ func NewInlineQueryResultPhoto(resultID, photoURL, thumbURL string) *InlineQuery
 	}
 }
 
+// NewInlineQueryResultVenue creates a new inline query result with venue.
 func NewInlineQueryResultVenue(resultID, title, address string, latitude, longitude float32) *InlineQueryResultVenue {
 	return &InlineQueryResultVenue{
 		Type:      TypeVenue,
@@ -160,6 +186,7 @@ func NewInlineQueryResultVenue(resultID, title, address string, latitude, longit
 	}
 }
 
+// NewInlineQueryResultVideo creates a new inline query result with video.
 func NewInlineQueryResultVideo(resultID, videoURL, mimeType, thumbURL, title string) *InlineQueryResultVideo {
 	return &InlineQueryResultVideo{
 		Type:     TypeVideo,
@@ -171,6 +198,7 @@ func NewInlineQueryResultVideo(resultID, videoURL, mimeType, thumbURL, title str
 	}
 }
 
+// NewInlineQueryResultVoice creates a new inline query result with voice.
 func NewInlineQueryResultVoice(resultID, voiceURL, title string) *InlineQueryResultVoice {
 	return &InlineQueryResultVoice{
 		Type:     TypeVoice,
diff --git a/utils_input.go b/utils_input.go
index 63bf430..d516c0d 100644
--- a/utils_input.go
+++ b/utils_input.go
@@ -1,11 +1,13 @@
 package telegram
 
+// NewInputTextMessageContent creates a new text of message.
 func NewInputTextMessageContent(messageText string) *InputTextMessageContent {
 	return &InputTextMessageContent{
 		MessageText: messageText,
 	}
 }
 
+// NewInputLocationMessageContent creates a new location.
 func NewInputLocationMessageContent(latitude, longitude float32) *InputLocationMessageContent {
 	return &InputLocationMessageContent{
 		Latitude:  latitude,
@@ -13,6 +15,7 @@ func NewInputLocationMessageContent(latitude, longitude float32) *InputLocationM
 	}
 }
 
+// NewInputVenueMessageContent creates a new venue.
 func NewInputVenueMessageContent(latitude, longitude float32, title, address string) *InputVenueMessageContent {
 	return &InputVenueMessageContent{
 		Latitude:  latitude,
@@ -22,6 +25,7 @@ func NewInputVenueMessageContent(latitude, longitude float32, title, address str
 	}
 }
 
+// NewInputContactMessageContent creates a new contact.
 func NewInputContactMessageContent(phoneNumber, firstName string) *InputContactMessageContent {
 	return &InputContactMessageContent{
 		PhoneNumber: phoneNumber,
@@ -29,6 +33,7 @@ func NewInputContactMessageContent(phoneNumber, firstName string) *InputContactM
 	}
 }
 
+// NewInputMediaPhoto creates a new photo in media album.
 func NewInputMediaPhoto(media string) *InputMediaPhoto {
 	return &InputMediaPhoto{
 		Type:  TypePhoto,
@@ -36,6 +41,7 @@ func NewInputMediaPhoto(media string) *InputMediaPhoto {
 	}
 }
 
+// NewInputMediaVideo creates a new video in media album.
 func NewInputMediaVideo(media string) *InputMediaVideo {
 	return &InputMediaVideo{
 		Type:  TypeVideo,
diff --git a/utils_keyboard.go b/utils_keyboard.go
index 7ce5a9d..ed4146c 100644
--- a/utils_keyboard.go
+++ b/utils_keyboard.go
@@ -1,5 +1,6 @@
 package telegram
 
+// NewReplyKeyboardRemove just hides keyboard.
 func NewReplyKeyboardRemove(selective bool) *ReplyKeyboardRemove {
 	return &ReplyKeyboardRemove{
 		RemoveKeyboard: true,
@@ -7,27 +8,29 @@ func NewReplyKeyboardRemove(selective bool) *ReplyKeyboardRemove {
 	}
 }
 
+// NewReplyKeyboardMarkup creates new keyboard markup of simple buttons.
 func NewReplyKeyboardMarkup(rows ...[]KeyboardButton) *ReplyKeyboardMarkup {
 	var keyboard [][]KeyboardButton
 	keyboard = append(keyboard, rows...)
-	return &ReplyKeyboardMarkup{
-		Keyboard:       keyboard,
-		ResizeKeyboard: true,
-	}
+	return &ReplyKeyboardMarkup{Keyboard: keyboard}
 }
 
+// NewReplyKeyboardRow creates new keyboard row for buttons.
 func NewReplyKeyboardRow(buttons ...KeyboardButton) []KeyboardButton {
 	var row []KeyboardButton
 	row = append(row, buttons...)
 	return row
 }
 
+// NewReplyKeyboardButton creates new button with custom text for sending it.
 func NewReplyKeyboardButton(text string) KeyboardButton {
 	return KeyboardButton{
 		Text: text,
 	}
 }
 
+// NewReplyKeyboardButtonContact creates new button with custom text for sending
+// user contact.
 func NewReplyKeyboardButtonContact(text string) KeyboardButton {
 	return KeyboardButton{
 		Text:           text,
@@ -35,6 +38,8 @@ func NewReplyKeyboardButtonContact(text string) KeyboardButton {
 	}
 }
 
+// NewReplyKeyboardButtonLocation creates new button with custom text for sending
+// user location.
 func NewReplyKeyboardButtonLocation(text string) KeyboardButton {
 	return KeyboardButton{
 		Text:            text,
diff --git a/utils_member.go b/utils_member.go
index dae9dd8..78c1bbc 100644
--- a/utils_member.go
+++ b/utils_member.go
@@ -2,54 +2,37 @@ package telegram
 
 import "time"
 
+// IsCreator checks that current member is creator.
 func (member *ChatMember) IsCreator() bool {
-	if member == nil {
-		return false
-	}
-
-	return member.Status == StatusCreator
+	return member != nil && member.Status == StatusCreator
 }
 
+// IsAdministrator checks that current member is administrator.
 func (member *ChatMember) IsAdministrator() bool {
-	if member == nil {
-		return false
-	}
-
-	return member.Status == StatusAdministrator
+	return member != nil && member.Status == StatusAdministrator
 }
 
+// IsMember checks that current member is a member.
 func (member *ChatMember) IsMember() bool {
-	if member == nil {
-		return false
-	}
-
-	return member.Status == StatusMember
+	return member != nil && member.Status == StatusMember
 }
 
+// IsRestricted checks that current member has been restricted.
 func (member *ChatMember) IsRestricted() bool {
-	if member == nil {
-		return false
-	}
-
-	return member.Status == StatusRestricted
+	return member != nil && member.Status == StatusRestricted
 }
 
+// IsLeft checks that current member has left the chat.
 func (member *ChatMember) IsLeft() bool {
-	if member == nil {
-		return false
-	}
-
-	return member.Status == StatusLeft
+	return member != nil && member.Status == StatusLeft
 }
 
+// IsKicked checks that current member has been kicked.
 func (member *ChatMember) IsKicked() bool {
-	if member == nil {
-		return false
-	}
-
-	return member.Status == StatusKicked
+	return member != nil && member.Status == StatusKicked
 }
 
+// UntilTime parse UntilDate of restrictions and returns time.Time.
 func (member *ChatMember) UntilTime() time.Time {
 	if member == nil {
 		return time.Time{}
diff --git a/utils_message.go b/utils_message.go
index db3143a..039b0b8 100644
--- a/utils_message.go
+++ b/utils_message.go
@@ -5,42 +5,44 @@ import (
 	"time"
 )
 
-func (msg *Message) IsCommand(command string) bool {
-	if !msg.IsText() {
-		return false
-	}
-
-	if !msg.HasEntities() {
+// IsCommand checks that the current message is a bot command.
+func (msg *Message) IsCommand() bool {
+	if !msg.IsText() || !msg.HasEntities() {
 		return false
 	}
 
 	entity := msg.Entities[0]
-	isBotCommand := entity.IsBotCommand() && entity.Offset == 0
-	if command != "" {
-		return isBotCommand && strings.EqualFold(msg.Command(), command)
-	}
-
-	return isBotCommand
+	return entity.IsBotCommand() && entity.Offset == 0
 }
 
+// IsCommandEqual checks that the current message is a specific bot command.
+func (msg *Message) IsCommandEqual(command string) bool {
+	return msg.IsCommand() && strings.EqualFold(msg.Command(), command)
+}
+
+// Command returns identifier of the bot command without bot username, if it was
+// available
 func (msg *Message) Command() string {
-	if !msg.IsCommand("") {
+	if !msg.IsCommand() {
 		return ""
 	}
 
 	return strings.Split(msg.RawCommand(), "@")[0]
 }
 
+// RawCommand returns identifier of the bot command with bot username, if it was
+// available
 func (msg *Message) RawCommand() string {
-	if !msg.IsCommand("") {
+	if !msg.IsCommand() {
 		return ""
 	}
 
 	return string([]rune(msg.Text)[1:msg.Entities[0].Length])
 }
 
+// HasCommandArgument checks that the current command message contains argument.
 func (msg *Message) HasCommandArgument() bool {
-	if !msg.IsCommand("") {
+	if !msg.IsCommand() {
 		return false
 	}
 
@@ -52,6 +54,7 @@ func (msg *Message) HasCommandArgument() bool {
 	return len([]rune(msg.Text)) != entity.Length
 }
 
+// CommandArgument returns raw command argument.
 func (msg *Message) CommandArgument() string {
 	if !msg.HasCommandArgument() {
 		return ""
@@ -60,22 +63,17 @@ func (msg *Message) CommandArgument() string {
 	return string([]rune(msg.Text)[msg.Entities[0].Length+1:])
 }
 
+// IsReply checks that the current message is a reply on other message.
 func (msg *Message) IsReply() bool {
-	if msg == nil {
-		return false
-	}
-
-	return msg.ReplyToMessage != nil
+	return msg != nil && msg.ReplyToMessage != nil
 }
 
+// IsForward checks that the current message is a forward of other message.
 func (msg *Message) IsForward() bool {
-	if msg == nil {
-		return false
-	}
-
-	return msg.ForwardFrom != nil
+	return msg != nil && msg.ForwardFrom != nil
 }
 
+// Time parse current message Date and returns time.Time.
 func (msg *Message) Time() time.Time {
 	if msg == nil {
 		return time.Time{}
@@ -84,6 +82,7 @@ func (msg *Message) Time() time.Time {
 	return time.Unix(msg.Date, 0)
 }
 
+// ForwardTime parse current message ForwardDate and returns time.Time.
 func (msg *Message) ForwardTime() time.Time {
 	if msg == nil {
 		return time.Time{}
@@ -92,131 +91,157 @@ func (msg *Message) ForwardTime() time.Time {
 	return time.Unix(msg.ForwardDate, 0)
 }
 
+// EditTime parse current message EditDate and returns time.Time.
 func (msg *Message) EditTime() time.Time {
 	var t time.Time
-	if msg == nil {
-		return t
-	}
-
-	if !msg.HasBeenEdited() {
+	if msg == nil || !msg.HasBeenEdited() {
 		return t
 	}
 
 	return time.Unix(msg.EditDate, 0)
 }
 
+// HasBeenEdited checks that the current message has been edited.
 func (msg *Message) HasBeenEdited() bool {
-	if msg == nil {
-		return false
-	}
-
-	return msg.EditDate > 0
+	return msg != nil && msg.EditDate > 0
 }
 
+// IsText checks that the current message is just a text message.
 func (msg *Message) IsText() bool {
-	if msg == nil {
-		return false
-	}
-
-	return msg.Text != ""
+	return msg != nil && msg.Text != ""
 }
 
+// IsAudio checks that the current message is a audio.
 func (msg *Message) IsAudio() bool {
 	return !msg.IsText() && msg.Audio != nil
 }
 
+// IsDocument checks that the current message is a document.
 func (msg *Message) IsDocument() bool {
 	return !msg.IsText() && msg.Document != nil
 }
 
+// IsGame checks that the current message is a game.
 func (msg *Message) IsGame() bool {
 	return !msg.IsText() && msg.Game != nil
 }
 
+// IsPhoto checks that the current message is a photo.
 func (msg *Message) IsPhoto() bool {
 	return !msg.IsText() && len(msg.Photo) > 0
 }
 
+// IsSticker checks that the current message is a sticker.
 func (msg *Message) IsSticker() bool {
 	return !msg.IsText() && msg.Sticker != nil
 }
 
+// IsVideo checks that the current message is a video.
 func (msg *Message) IsVideo() bool {
 	return !msg.IsText() && msg.Video != nil
 }
 
+// IsVoice checks that the current message is a voice.
 func (msg *Message) IsVoice() bool {
 	return !msg.IsText() && msg.Voice != nil
 }
 
+// IsVideoNote checks that the current message is a video note.
 func (msg *Message) IsVideoNote() bool {
 	return !msg.IsText() && msg.VideoNote != nil
 }
 
+// IsContact checks that the current message is a contact.
 func (msg *Message) IsContact() bool {
 	return !msg.IsText() && msg.Contact != nil
 }
 
+// IsLocation checks that the current message is a location.
 func (msg *Message) IsLocation() bool {
 	return !msg.IsText() && msg.Location != nil
 }
 
+// IsVenue checks that the current message is a venue.
 func (msg *Message) IsVenue() bool {
 	return !msg.IsText() && msg.Venue != nil
 }
 
+// IsNewChatMembersEvent checks that the current message is a event of entry of
+// new members.
 func (msg *Message) IsNewChatMembersEvent() bool {
 	return !msg.IsText() && len(msg.NewChatMembers) > 0
 }
 
+// IsLeftChatMemberEvent checks that the current message is a event of members
+// exit.
 func (msg *Message) IsLeftChatMemberEvent() bool {
 	return !msg.IsText() && msg.LeftChatMember != nil
 }
 
+// IsNewChatTitleEvent checks that the current message is a event of setting a
+// new chat title.
 func (msg *Message) IsNewChatTitleEvent() bool {
 	return !msg.IsText() && msg.NewChatTitle != ""
 }
 
+// IsNewChatPhotoEvent checks that the current message is a event of setting a
+// new chat avatar.
 func (msg *Message) IsNewChatPhotoEvent() bool {
 	return !msg.IsText() && len(msg.NewChatPhoto) > 0
 }
 
+// IsDeleteChatPhotoEvent checks that the current message is a event of deleting
+// a chat avatar.
 func (msg *Message) IsDeleteChatPhotoEvent() bool {
 	return !msg.IsText() && msg.DeleteChatPhoto
 }
 
+// IsGroupChatCreatedEvent checks that the current message is a event of creating
+// a new group.
 func (msg *Message) IsGroupChatCreatedEvent() bool {
 	return !msg.IsText() && msg.GroupChatCreated
 }
 
+// IsSupergroupChatCreatedEvent checks that the current message is a event of
+// creating a new supergroup.
 func (msg *Message) IsSupergroupChatCreatedEvent() bool {
 	return !msg.IsText() && msg.SupergroupChatCreated
 }
 
+// IsChannelChatCreatedEvent checks that the current message is a event of
+// creating a new channel.
 func (msg *Message) IsChannelChatCreatedEvent() bool {
 	return !msg.IsText() && msg.ChannelChatCreated
 }
 
+// IsPinnedMessage checks that the current message is a event of pinning another
+// message.
 func (msg *Message) IsPinnedMessage() bool {
 	return !msg.IsText() && msg.PinnedMessage != nil
 }
 
+// IsInvoice checks that the current message is a invoice.
 func (msg *Message) IsInvoice() bool {
 	return !msg.IsText() && msg.Invoice != nil
 }
 
+// IsSuccessfulPayment checks that the current message is a event of successful
+// payment.
 func (msg *Message) IsSuccessfulPayment() bool {
 	return !msg.IsText() && msg.SuccessfulPayment != nil
 }
 
+// HasEntities checks that the current message contains entities.
 func (msg *Message) HasEntities() bool {
 	return msg.IsText() && len(msg.Entities) > 0
 }
 
+// HasCaptionEntities checks that the current media contains entities in caption.
 func (msg *Message) HasCaptionEntities() bool {
 	return !msg.IsText() && len(msg.CaptionEntities) > 0
 }
 
+// HasMentions checks that the current message contains mentions.
 func (msg *Message) HasMentions() bool {
 	if !msg.HasEntities() {
 		return false
@@ -231,6 +256,7 @@ func (msg *Message) HasMentions() bool {
 	return false
 }
 
+// HasCaptionMentions checks that the current media contains mentions in caption.
 func (msg *Message) HasCaptionMentions() bool {
 	if !msg.HasCaptionEntities() {
 		return false
@@ -245,14 +271,12 @@ func (msg *Message) HasCaptionMentions() bool {
 	return false
 }
 
+// HasCaption checks that the current media has caption.
 func (msg *Message) HasCaption() bool {
 	return !msg.IsText() && msg.Caption != ""
 }
 
+// HasAuthorSignature checks that the current channel post has author signature.
 func (msg *Message) HasAuthorSignature() bool {
-	if msg == nil {
-		return false
-	}
-
-	return msg.AuthorSignature != ""
+	return msg != nil && msg.AuthorSignature != ""
 }
diff --git a/utils_update.go b/utils_update.go
index 43e3ce7..bdf80d4 100644
--- a/utils_update.go
+++ b/utils_update.go
@@ -10,8 +10,11 @@ import (
 	http "github.com/valyala/fasthttp"
 )
 
+// UpdatesChannel is a channel for reading updates of bot.
 type UpdatesChannel <-chan Update
 
+// NewLongPollingChannel creates channel for receive incoming updates using long
+// polling.
 func (bot *Bot) NewLongPollingChannel(params *GetUpdatesParameters) UpdatesChannel {
 	if params == nil {
 		params = &GetUpdatesParameters{
@@ -44,6 +47,8 @@ func (bot *Bot) NewLongPollingChannel(params *GetUpdatesParameters) UpdatesChann
 	return channel
 }
 
+// NewWebhookChannel creates channel for receive incoming updates via an outgoing
+// webhook.
 func (bot *Bot) NewWebhookChannel(params *SetWebhookParameters, certFile, keyFile, set, listen, serve string) (updates UpdatesChannel) {
 	if params == nil {
 		params = &SetWebhookParameters{
@@ -92,74 +97,50 @@ func (bot *Bot) NewWebhookChannel(params *SetWebhookParameters, certFile, keyFil
 	return channel
 }
 
+// IsMessage checks that the current update is a message creation event.
 func (upd *Update) IsMessage() bool {
-	if upd == nil {
-		return false
-	}
-
-	return upd.Message != nil
+	return upd != nil && upd.Message != nil
 }
 
+// IsEditedMessage checks that the current update is a editing message event.
 func (upd *Update) IsEditedMessage() bool {
-	if upd == nil {
-		return false
-	}
-
-	return upd.EditedMessage != nil
+	return upd != nil && upd.EditedMessage != nil
 }
 
+// IsChannelPost checks that the current update is a post channel creation event.
 func (upd *Update) IsChannelPost() bool {
-	if upd == nil {
-		return false
-	}
-
-	return upd.ChannelPost != nil
+	return upd != nil && upd.ChannelPost != nil
 }
 
+// IsEditedChannelPost checks that the current update is a editing post channel
+// event.
 func (upd *Update) IsEditedChannelPost() bool {
-	if upd == nil {
-		return false
-	}
-
-	return upd.EditedChannelPost != nil
+	return upd != nil && upd.EditedChannelPost != nil
 }
 
+// IsInlineQuery checks that the current update is a inline query update.
 func (upd *Update) IsInlineQuery() bool {
-	if upd == nil {
-		return false
-	}
-
-	return upd.InlineQuery != nil
+	return upd != nil && upd.InlineQuery != nil
 }
 
+// IsChosenInlineResult checks that the current update is a chosen inline result
+// update.
 func (upd *Update) IsChosenInlineResult() bool {
-	if upd == nil {
-		return false
-	}
-
-	return upd.ChosenInlineResult != nil
+	return upd != nil && upd.ChosenInlineResult != nil
 }
 
+// IsCallbackQuery checks that the current update is a callback query update.
 func (upd *Update) IsCallbackQuery() bool {
-	if upd == nil {
-		return false
-	}
-
-	return upd.CallbackQuery != nil
+	return upd != nil && upd.CallbackQuery != nil
 }
 
+// IsShippingQuery checks that the current update is a shipping query update.
 func (upd *Update) IsShippingQuery() bool {
-	if upd == nil {
-		return false
-	}
-
-	return upd.ShippingQuery != nil
+	return upd != nil && upd.ShippingQuery != nil
 }
 
+// IsPreCheckoutQuery checks that the current update is a pre checkout query
+// update.
 func (upd *Update) IsPreCheckoutQuery() bool {
-	if upd == nil {
-		return false
-	}
-
-	return upd.PreCheckoutQuery != nil
+	return upd != nil && upd.PreCheckoutQuery != nil
 }
diff --git a/utils_user.go b/utils_user.go
index 5ebf53d..ec3ad28 100644
--- a/utils_user.go
+++ b/utils_user.go
@@ -6,6 +6,7 @@ import (
 	"golang.org/x/text/language"
 )
 
+// Language parse LanguageCode of current user and returns language.Tag.
 func (user *User) Language() *language.Tag {
 	if user == nil {
 		return nil
@@ -19,6 +20,8 @@ func (user *User) Language() *language.Tag {
 	return &tag
 }
 
+// FullName returns the full name of user or FirstName if LastName is not
+// available.
 func (user *User) FullName() string {
 	if user == nil {
 		return ""
diff --git a/variables.go b/variables.go
new file mode 100644
index 0000000..0e4dd9a
--- /dev/null
+++ b/variables.go
@@ -0,0 +1,8 @@
+package telegram
+
+import "net/url"
+
+var defaultURI = &url.URL{
+	Scheme: "https",
+	Host:   "api.telegram.org",
+}