(host, port) of the current standalone, primary, or mongos, or None.

        Accessing :attr:`address` raises :exc:`~.errors.InvalidOperation` if
        the client is load-balancing among mongoses, since there is no single
        address. Use :attr:`nodes` instead.

        If the client is not connected, this will block until a connection is
        established or raise ServerSelectionTimeoutError if no server is
        available.

        .. versionadded:: 3.0

def address(self):
        """(host, port) of the current standalone, primary, or mongos, or None.

        Accessing :attr:`address` raises :exc:`~.errors.InvalidOperation` if
        the client is load-balancing among mongoses, since there is no single
        address. Use :attr:`nodes` instead.

        If the client is not connected, this will block until a connection is
        established or raise ServerSelectionTimeoutError if no server is
        available.

        .. versionadded:: 3.0
        """
        topology_type = self._topology._description.topology_type
        if topology_type == TOPOLOGY_TYPE.Sharded:
            raise InvalidOperation(
                'Cannot use "address" property when load balancing among'
                ' mongoses, use "nodes" instead.')
        if topology_type not in (TOPOLOGY_TYPE.ReplicaSetWithPrimary,
                                 TOPOLOGY_TYPE.Single):
            return None
        return self._server_property('address')