const INF=(0).MAX;
fcn dijkstra(graph,start,dst){
   Q   :=graph.copy();
   prev:=graph.keys.pump(Dictionary().add.fp1(Void));
   dist:=graph.keys.pump(Dictionary().add.fp1(INF));
   dist[start]=0;
   while(Q){
      Q.reduce('wrap(min,[(v,_)],ru){
           if((d:=dist[v])<min){ ru.set(v); d } else min },
        INF,ru:=Ref(Void));
      if(not u:=ru.value) return("Can't get there");
      if(u==dst){
         S:=List(); do{ S.append(u); u=prev[u]; }while(u);
	 return(S.reverse());
      }
      Q.del(u);
      foreach v,len in (graph[u]){  // (neighborVertex,len to neighbor)...
	  alt:=dist[u] + len;
	  if(alt<dist[v]){ dist[v]=alt; prev[v]=u; }
      }
   }
}