def _parseServer(self, reactor, domain, index):
        """
        Internal parser function for L{_parseServer} to convert the string
        arguments for a systemd server endpoint into structured arguments for
        L{AdoptedStreamServerEndpoint}.

        @param reactor: An L{IReactorSocket} provider.

        @param domain: The domain (or address family) of the socket inherited
            from systemd.  This is a string like C{"INET"} or C{"UNIX"}, ie the
            name of an address family from the L{socket} module, without the
            C{"AF_"} prefix.
        @type domain: C{str}

        @param index: An offset into the list of file descriptors inherited from
            systemd.
        @type index: C{str}

        @return: A two-tuple of parsed positional arguments and parsed keyword
            arguments (a tuple and a dictionary).  These can be used to
            construct an L{AdoptedStreamServerEndpoint}.
        """
        index = int(index)
        fileno = self._sddaemon.inheritedDescriptors()[index]
        addressFamily = getattr(socket, 'AF_' + domain)
        return AdoptedStreamServerEndpoint(reactor, fileno, addressFamily)

        Internal parser function for L{_parseServer} to convert the string
        arguments for a systemd server endpoint into structured arguments for
        L{AdoptedStreamServerEndpoint}.

        @param reactor: An L{IReactorSocket} provider.

        @param domain: The domain (or address family) of the socket inherited
            from systemd.  This is a string like C{"INET"} or C{"UNIX"}, ie the
            name of an address family from the L{socket} module, without the
            C{"AF_"} prefix.
        @type domain: C{str}

        @param index: An offset into the list of file descriptors inherited from
            systemd.
        @type index: C{str}

        @return: A two-tuple of parsed positional arguments and parsed keyword
            arguments (a tuple and a dictionary).  These can be used to
            construct an L{AdoptedStreamServerEndpoint}.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/internet/endpoints.py