如何使用用户名向我的电报机器人发送消息

I am using the telepot python library, I know that you can send a message when you have someone's UserID(Which is a number). I wanna know if it is possible to send a message to someone without having their UserID but only with their username(The one which starts with '@'), Also if there is a way to convert a username to a UserID.I am using the telepot python library, I know t