///|
test {
  fn find_neighbors() -> Array[Int] {
    let graph = Graph::new()
    graph.add_nodes_from([0, 1, 2, 3, 4, 5])
    graph.add_edges_from([(1, 2), (2, 5)])
    println(graph)
    graph.neighbors(2)
  }
  fn get_in_degree() -> Int {
    let graph = DiGraph::new()
    graph.add_nodes_from([0, 1, 2, 3, 4, 5])
    graph.add_edges_from([(1, 2), (2, 5)])
    println(graph)
    graph.out_degree(2)
  }
  inspect(find_neighbors(), content="[1, 5]")
  inspect(get_in_degree(), content="1")
}