graph:=Dictionary(  // directed graph
   "a", T(T("b", 7.0), T("c", 9.0), T("f",14.0)),
   "b", T(T("c",10.0), T("d",15.0)),
   "c", T(T("d",11.0), T("f", 2.0)),
   "d", T(T("e", 6.0)),
   "e", T(T("f", 9.0)),
   "f", T,
);
dijkstra(graph,"a","e").println();
dijkstra(graph,"e","a").println();