code: def _try_trigger_before_first_request_funcs(self):  # pylint: disable=C0103
          
          if self._after_first_request_handled:
              return
          else:
              with self._before_first_request_lock:
                  if self._after_first_request_handled:
                      return
                  for func in self._before_first_request_funcs:
                      func()
                  self._after_first_request_handled = True
docs: Runs each function from ``self.before_first_request_funcs`` once and only once.