title: How can I send a message to someone with my telegram bot using their Username
body: <p>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.</p>