Method link

celery/canvas.py:1670–1679

(self, sig)

            visitor.on_group_end(self, **headers)

    def link(self, sig):
        # Simply link to first task. Doing this is slightly misleading because
        # the callback may be executed before all children in the group are
        # completed and also if any children other than the first one fail.
        #
        # The callback signature is cloned and made immutable since it the
        # first task isn't actually capable of passing the return values of its
        # siblings to the callback task.
        sig = sig.clone().set(immutable=True)
        return self.tasks[0].link(sig)

    def link_error(self, sig):
        # Any child task might error so we need to ensure that they are all