code: function(types, callback, scope){
              types = types || [];
              var args = [].slice.call(arguments);
  
              if($.isString(types)){
                  types = types.split(',');
              }
              var len = types.length;
              if(len===0){
                  return this;
              }
              args = args.length > 3 ? args.splice(3, args.length-1) : [];
              for(var i = 0;i<len;i++){
                  var type = types[i];
                  _cache[type] = _cache[type] || [];
                  _cache[type].push({callback:callback,scope:scope,args:args});
              }
              return this;
          }
docs: 订阅广播事件
  @param  {[type]}   types     事件类型，支持,分隔符
  @param  {Function} callback 回调函数
  @param  {[type]}   scope    回调函数上下文
  @return {[type]}            this