'Set specific topics to track for metadata.
Arguments:
topics (list of str): topics to check for metadata
Returns:
Future: resolves after metadata request/response'

def set_topics(self, topics):

    if set(topics).difference(self._topics):
        future = self.cluster.request_update()
    else:
        future = Future().success(set(topics))
    self._topics = set(topics)
    return future
