'Return set of replica set member addresses.'

def _get_replica_set_members(self, selector):

    with self._lock:
        topology_type = self._description.topology_type
        if (topology_type not in (TOPOLOGY_TYPE.ReplicaSetWithPrimary, TOPOLOGY_TYPE.ReplicaSetNoPrimary)):
            return set()
        return set([sd.address for sd in selector(self._new_selection())])
