def _postprocess_nodes(
        self, nodes: List[NodeWithScore], query: Any = None
    ) -> List[NodeWithScore]:
        """Add a prefix to each node's text."""
        for node in nodes:
            if isinstance(node.node, TextNode):
                node.node.text = f"PROCESSED: {node.node.text}"
        return nodes
Add a prefix to each node's text.
llama-index-core/tests/memory/blocks/test_vector.py