code: func CreateaSenderIdentity() {
  	apiKey := os.Getenv("SENDGRID_API_KEY")
  	host := "https://api.sendgrid.com"
  	request := sendgrid.GetRequest(apiKey, "/v3/senders", host)
  	request.Method = "POST"
  	request.Body = []byte(` {
    "address": "123 Elm St.", 
    "address_2": "Apt. 456", 
    "city": "Denver", 
    "country": "United States", 
    "from": {
      "email": "from@example.com", 
      "name": "Example INC"
    }, 
    "nickname": "My Sender ID", 
    "reply_to": {
      "email": "replyto@example.com", 
      "name": "Example INC"
    }, 
    "state": "Colorado", 
    "zip": "80202"
  }`)
  	response, err := sendgrid.API(request)
  	if err != nil {
  		log.Println(err)
  	} else {
  		fmt.Println(response.StatusCode)
  		fmt.Println(response.Body)
  		fmt.Println(response.Headers)
  	}
  }
docs: // CreateaSenderIdentity : Create a Sender Identity
  // POST /senders