code: def connect(self, cback, subscribers=None, instance=None):
          
          if subscribers is None:
              subscribers = self.subscribers
          # wrapper
          if self._fconnect is not None:
              def _connect(cback):
                  self._connect(subscribers, cback)
  
              notify = partial(self._notify_one, instance)
              if instance is not None:
                  result = self._fconnect(instance, cback, subscribers,
                                          _connect, notify)
              else:
                  result = self._fconnect(cback, subscribers, _connect, notify)
              if inspect.isawaitable(result):
                  result = pull_result(result)
          else:
              self._connect(subscribers, cback)
              result = None
          return result
docs: Add  a function or a method as an handler of this signal.
          Any handler added can be a coroutine.
  
          :param cback: the callback (or *handler*) to be added to the set
          :returns: ``None`` or the value returned by the corresponding wrapper