def lookupMailGroup(name, timeout=None):
        """
        Perform an MG record lookup.

        @type name: C{str}
        @param name: DNS name to resolve.

        @type timeout: Sequence of C{int}
        @param timeout: Number of seconds after which to reissue the query.
            When the last timeout expires, the query is considered failed.

        @rtype: L{Deferred}
        @return: A L{Deferred} which fires with a three-tuple of lists of
            L{twisted.names.dns.RRHeader} instances.  The first element of the
            tuple gives answers.  The second element of the tuple gives
            authorities.  The third element of the tuple gives additional
            information.  The L{Deferred} may instead fail with one of the
            exceptions defined in L{twisted.names.error} or with
            C{NotImplementedError}.
        """

        Perform an MG record lookup.

        @type name: C{str}
        @param name: DNS name to resolve.

        @type timeout: Sequence of C{int}
        @param timeout: Number of seconds after which to reissue the query.
            When the last timeout expires, the query is considered failed.

        @rtype: L{Deferred}
        @return: A L{Deferred} which fires with a three-tuple of lists of
            L{twisted.names.dns.RRHeader} instances.  The first element of the
            tuple gives answers.  The second element of the tuple gives
            authorities.  The third element of the tuple gives additional
            information.  The L{Deferred} may instead fail with one of the
            exceptions defined in L{twisted.names.error} or with
            C{NotImplementedError}.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/internet/interfaces.py