'Called by impl when a message is delivered for a consumer
:param Channel channel: The implementation channel object
:param spec.Basic.Deliver method:
:param pika.spec.BasicProperties properties: message properties
:param body: delivered message body; empty string if no body
:type body: str, unicode, or bytes (python 3.x)'

def _on_consumer_message_delivery(self, _channel, method, properties, body):

    evt = _ConsumerDeliveryEvt(method, properties, body)
    consumer = self._consumer_infos[method.consumer_tag]
    if (consumer.alternate_event_sink is not None):
        consumer.alternate_event_sink(evt)
    else:
        self._add_pending_event(evt)
