def METHOD_NAME(node: torch.fx.Node) -> None:
    def _check_is_fake_tensor(val):
        if isinstance(val, FakeTensor):
            return True
        if isinstance(val, Iterable):
            return all(_check_is_fake_tensor(x) for x in val)
        return False
    val = node.meta.get("val", None)
    if val is None or not _check_is_fake_tensor(val):
        raise SpecViolationError(f"Node.meta {node.name} is missing val field.")