<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _triggering_ctx(self):
 """ Context manager that ensures that a hook is not re-triggered by one of its handlers. """

        if self._is_triggering:
            raise RuntimeError('{} cannot be triggered while it is being handled'.format(self))
        self._is_triggering = True
        try:
            yield self
        finally:
            self._is_triggering = False