'Async version of get_multi().
Returns:
A UserRPC instance whose get_result() method returns {} if
there was a network error, otherwise a dict just like
get_multi() returns.'

def get_multi_async(self, keys, key_prefix='', namespace=None, for_cas=False, rpc=None):

    request = MemcacheGetRequest()
    self._add_app_id(request)
    _add_name_space(request, namespace)
    if for_cas:
        request.set_for_cas(True)
    response = MemcacheGetResponse()
    user_key = {}
    for key in keys:
        request.add_key(_key_string(key, key_prefix, user_key))
    return self._make_async_call(rpc, 'Get', request, response, self.__get_hook, user_key)
