code: def group(self, *args, **kwargs):
          
          def decorator(f):
              cmd = group(*args, **kwargs)(f)
              self.add_command(cmd)
              return cmd
          return decorator
docs: A shortcut decorator for declaring and attaching a group to
          the group.  This takes the same arguments as :func:`group` but
          immediately registers the created command with this instance by
          calling into :meth:`add_command`.