code: func (m *Message) CommandWithAt() string {
  	if !m.IsCommand() {
  		return ""
  	}
  
  	// IsCommand() checks that the message begins with a bot_command entity
  	entity := (*m.Entities)[0]
  	return m.Text[1:entity.Length]
  }
docs: // CommandWithAt checks if the message was a command and if it was, returns the
  // command. If the Message was not a command, it returns an empty string.
  //
  // If the command contains the at name syntax, it is not removed. Use Command()
  // if you want that.