def connect(self, protocolFactory):
        """
        Implement L{IStreamClientEndpoint.connect} to launch a child process
        and connect it to a protocol created by C{protocolFactory}.

        @param protocolFactory: A factory for an L{IProtocol} provider which
            will be notified of all events related to the created process.
        """
        proto = protocolFactory.buildProtocol(_ProcessAddress())
        try:
            self._spawnProcess(
                _WrapIProtocol(proto, self._executable, self._errFlag),
                self._executable, self._args, self._env, self._path, self._uid,
                self._gid, self._usePTY, self._childFDs)
        except:
            return defer.fail()
        else:
            return defer.succeed(proto)

        Implement L{IStreamClientEndpoint.connect} to launch a child process
        and connect it to a protocol created by C{protocolFactory}.

        @param protocolFactory: A factory for an L{IProtocol} provider which
            will be notified of all events related to the created process.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/internet/endpoints.py