Returns the index of node n in the list of nodes.
auto g1 = Graph!(int, int)([1, 2]); auto e1 = g1.edge(1, 2, 1); g1 ~= e1; assert(g1.indexOf(g1.edge(1, 2)) == 0); assertThrown!MissingEdgeException(g1.indexOf(g1.edge(1, 1)));
See Implementation
Returns the index of node n in the list of nodes.