code: def add_command(self, command, handler, prompt=True):
          
          if prompt:
              thehandler = self._create_autoprompt_handler(handler)
          else:
              thehandler = handler
          self.commands.add(command, thehandler)
docs: Registers a command.
  
          The command may be either a string (which is then automatically
          compiled into a regular expression), or a pre-compiled regular
          expression object.
  
          If the given response handler is a string, it is sent as the
          response to any command that matches the given regular expression.
          If the given response handler is a function, it is called
          with the command passed as an argument.
  
          :type  command: str|regex
          :param command: A string or a compiled regular expression.
          :type  handler: function|str
          :param handler: A string, or a response handler.
          :type  prompt: bool
          :param prompt: Whether to show a prompt after completing the command.