var QueryString = {
   params : $H(window.location.search.toQueryParams()),
  
   get : function(key, defaultValue) {
       if (defaultValue == null) defaultValue = null;
       var value = this.params.get(key);
       if (value==null) value = defaultValue;
       return value;
   },
  
   set : function(key, value) {
       this.params.set(key, value);
   },
  
   remove : function(key) {
       this.params.unset(key);
   },
  
   make : function() {
       return "?" + this.params.collect(function(param) {
           return escape(param.key) +"="+ escape(param.value);
       }).join("&");
   },
  
   go : function() {
       window.location.href = location.pathname + this.make();
   }
}