code: def command(self, name: str=None, hint: str=None, aliases: Sequence[str]=list()):
          
          def decorator(fn):
              _name = name or fn.__name__
              cmd = _Command(_name, hint, fn)
              self._commands[_name] = cmd
              for alias in aliases:
                  self._aliases[alias] = cmd
              return fn
          return decorator
docs: Register a command handler that will be invoked when a command is
          detected. If your handler has a docstring, it will be shown for
          .help [command]. The function will be invoked with *args set to the
          list of parameters given (as parsed by shlex.split). You may also
          include any of these keyword arguments in your signature:
  
          message:    the original message this was invoked in response to
          client:     the value of CommandSet.client
          cmdset:     this command set
  
          If your function returns a string, it will be given back to the user
          who issued the command.
  
          :param name: name of the command. Defaults to __name__ if None.
          :param hint: hint for the command (shown for .help).
          :param aliases: aliases for this command.