def parent_nodes(self):
        """The parent `Node`s.

        Returns:
            all the `Node`s whose output this node immediately depends on.
        """
        node_deps = []
        for kt in self.arguments.keras_tensors:
            op = kt._keras_history.operation
            node_index = kt._keras_history.node_index
            if op is not None:  # `None` for `Input` tensors.
                node_deps.append(op._inbound_nodes[node_index])
        return node_deps
The parent `Node`s.

        Returns:
            all the `Node`s whose output this node immediately depends on.
        
keras/src/ops/node.py