def command(self, *args, **kwargs):
def decorator(func):<EOL><INDENT>kwargs.setdefault('<STR_LIT>', self)<EOL>result = command(*args, **kwargs)(func)<EOL>self.add_command(result)<EOL>return result<EOL><DEDENT>return decorator<EOL>
A shortcut decorator that invokes :func:`.command` and adds it to
        the internal command list via :meth:`~.GroupMixin.add_command`.