'This is called when a synchronous command is completed. It will undo
the blocking state and send all the frames that stacked up while we
were in the blocking state.
:param pika.frame.Method method_frame_unused: The method frame received'

def _on_synchronous_complete(self, _method_frame_unused):

    LOGGER.debug('%i    blocked    frames', len(self._blocked))
    self._blocking = None
    while (self._blocked and (self._blocking is None)):
        self._rpc(*self._blocked.popleft())
