code: def nodes(self):
          
          description = self._topology.description
          return frozenset(s.address for s in description.known_servers)
docs: Set of all currently connected servers.
  
          .. warning:: When connected to a replica set the value of :attr:`nodes`
            can change over time as :class:`MongoClient`'s view of the replica
            set changes. :attr:`nodes` can also be an empty set when
            :class:`MongoClient` is first instantiated and hasn't yet connected
            to any servers, or a network partition causes it to lose connection
            to all servers.