message: Add a test for the new function
diff: @@ -283,6 +283,25 @@ fn multi() {
  assert_eq!(gr.edge_count(), 2);
  }
  +
  +#[test]
  +fn iter_multi_edges() {
  + let mut gr = Graph::new();
  + let a = gr.add_node("a");
  + let b = gr.add_node("b");
  + let c = gr.add_node("c");
  + gr.add_edge(a, b, ());
  + gr.add_edge(a, c, ());
  + gr.add_edge(a, b, ());
  + gr.add_edge(b, c, ());
  +
  + let mut iter = gr.edges_connecting(a, b);
  +
  + assert_eq!(EdgeIndex::new(2), iter.next().unwrap().id());
  + assert_eq!(EdgeIndex::new(0), iter.next().unwrap().id());
  + assert_eq!(None, iter.next());
  +}
  +
  #[test]
  fn update_edge()
  {
  