def _connect(self):
        """
        Establish a connection to the master process's UNIX listener socket,
        constructing a mitogen.master.Router to communicate with the master,
        and a mitogen.parent.Context to represent it.

        Depending on the original transport we should emulate, trigger one of
        the _connect_*() service calls defined above to cause the master
        process to establish the real connection on our behalf, or return a
        reference to the existing one.
        """
        if self.connected:
            return

        self._connect_broker()
        stack = self._build_stack()
        self._connect_stack(stack)
Establish a connection to the master process's UNIX listener socket,
        constructing a mitogen.master.Router to communicate with the master,
        and a mitogen.parent.Context to represent it.

        Depending on the original transport we should emulate, trigger one of
        the _connect_*() service calls defined above to cause the master
        process to establish the real connection on our behalf, or return a
        reference to the existing one.