code: def on_shutdown(self, broker):
          
          _v and LOG.debug('%r.on_shutdown(%r)', self, broker)
          fire(self, 'shutdown')
          for handle, (persist, fn) in self._handle_map.iteritems():
              _v and LOG.debug('%r.on_shutdown(): killing %r: %r', self, handle, fn)
              fn(Message.dead(self.broker_shutdown_msg))
docs: Called during :meth:`Broker.shutdown`, informs callbacks registered
          with :meth:`add_handle_cb` the connection is dead.