let edge = graph
    .add_edge(1, "shivam", "kapoor", [("p1", 100u64)], Some("fire_nation"))
    .unwrap();
edge.add_constant_properties([("z", true)], Some("fire_nation"))
    .unwrap();

let filter = PropertyFilter::property("z")
    .constant()
    .eq(Prop::map([("fire_nation", true)]));
assert_eq!(filter_edges(&graph, filter), vec!["shivam->kapoor"]);

graph.num_layers()