def connectionMade(self, protocol):
        """
        Called by associated L{dns.DNSProtocol} instances when they connect.
        """
        self.connections.append(protocol)
        for (d, q, t) in self.pending:
            self.queryTCP(q, t).chainDeferred(d)
        del self.pending[:]

        Called by associated L{dns.DNSProtocol} instances when they connect.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/names/client.py