func (bot *BotAPI) SetAPIEndpoint(apiEndpoint string) {
	bot.apiEndpoint = apiEndpoint
}
SetAPIEndpoint add telegram apiEndpont to Bot
package tgbotapi
import (
	"bytes"
	"encoding/json"
	"errors"
	"fmt"
	"io"
	"io/ioutil"
	"net/http"
	"net/url"
	"os"
	"strconv"
	"strings"
	"time"
	"github.com/technoweenie/multipartstreamer"
)
type HttpClient interface {
	Do(req *http.Request) (*http.Response, error)
}
type BotAPI struct {
	Token  string `json:"token"`
	Debug  bool   `json:"debug"`
	Buffer int    `json:"buffer"`
	Self            User       `json:"-"`
	Client          HttpClient `json:"-"`
	shutdownChannel chan interface{}
	apiEndpoint string
}
func NewBotAPI(token string) (*BotAPI, error) {
	return NewBotAPIWithClient(token, APIEndpoint, &http.Client{})
}
func NewBotAPIWithAPIEndpoint(token, apiEndpoint string) (*BotAPI, error) {
	return NewBotAPIWithClient(token, apiEndpoint, &http.Client{})
}
func NewBotAPIWithClient(token, apiEndpoint string, client HttpClient) (*BotAPI, error) {
	bot := &BotAPI{
		Token:           token,
		Client:          client,
		Buffer:          100,
		shutdownChannel: make(chan interface{}),
		apiEndpoint: apiEndpoint,
	}
	self, err := bot.GetMe()
	if err != nil {
		return nil, err
	}
	bot.Self = self
	return bot, nil
}