def get_ancestor_link(self, ancestor):
        """
        Returns the field on the current model which points to the given
        "ancestor". This is possible an indirect link (a pointer to a parent
        model, which points, eventually, to the ancestor). Used when
        constructing table joins for model inheritance.

        Returns None if the model isn't an ancestor of this one.
        """
        if self.parents in ancestor:
            return self.parents[ancestor]
        for parent in self.parents:
            # Tries to get a link field from the immediate parent
            parent_link = parent._meta.get_ancestor_link(ancestor)
            if parent_link:
                # In case of a proxied model, the first link
                # of the chain to the ancestor is that parent
                # links
                return self.parents[parent] or parent_link
dataset/ETHPy150Open CollabQ/CollabQ/vendor/django/db/models/options.py/Options.get_ancestor_link/swapped operands of `in`