addPage static method
Implementation
static addPage(String tag,num uid){
if(pageList.containsKey(tag)){
Queue<num> queue=pageList[tag]!;
queue.addFirst(uid);
pageList[tag]=queue;
}else{
Queue<num> queue=Queue();
queue.addFirst(uid);
pageList[tag]=queue;
}
// debugPrint("========${pageList.toString()}========");
}