def __call__(self, *args, **kwargs) -> Any:
        """When the client has navigated to a command, execute it"""
        if not isinstance(self._current_node, CommandGraphCall):
            raise SelectError("Invalid call", "", self._current_node.selectors)

        return self._command.execute(self._current_node, args, kwargs)
When the client has navigated to a command, execute it
libqtile/command/client.py