def _getPort(self):
        """
        Wrapper around the appropriate listen method of the reactor.

        @return: the port object returned by the listen method.
        @rtype: an object providing
            L{twisted.internet.interfaces.IListeningPort}.
        """
        return getattr(_maybeGlobalReactor(self.reactor),
                       'listen%s' % (self.method,))(*self.args, **self.kwargs)

        Wrapper around the appropriate listen method of the reactor.

        @return: the port object returned by the listen method.
        @rtype: an object providing
            L{twisted.internet.interfaces.IListeningPort}.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/application/internet.py