def lists(self) -> cabc.Iterable[tuple[K, list[V]]]:
        """Return a iterator of ``(key, values)`` pairs, where values is the list
        of all values associated with the key."""
        values: list[V]

        for key, values in super().items():  # type: ignore[assignment]
            yield key, list(values)
Return a iterator of ``(key, values)`` pairs, where values is the list
        of all values associated with the key.
src/werkzeug/datastructures/structures.py