fn try_load_from_disk_and_cache_in_memory<Qcx, K, V>(
    qcx: Qcx,
    key: &K,
    dep_node: &DepNode<Qcx::DepKind>,
    query: &QueryVTable<Qcx, K, V>
) -> Option<(V, DepNodeIndex)>where
    K: Clone,
    Qcx: QueryContext,
    V: Debug,