'Stores a list of messages, returning a list of any messages which could
not be stored.
One type of object must be able to be stored, ``Message``.'

def _store(self, messages, *args, **kwargs):

    lock(self.key)
    try:
        if messages:
            data = cache.get(self.key)
            if (not data):
                data = cPickle.dumps(([], True))
            data = cPickle.loads(data)
            data.append(messages)
            cache.set(self.key, cPickle.dumps(messages), 2592000)
        else:
            cache.set(self.key, cPickle.dumps([]), 2592000)
    except:
        pass
    unlock(self.key)
    return messages
