code: function (store, evtName, handler) {
      var args = [], len = arguments.length - 3;
      while ( len-- > 0 ) args[ len ] = arguments[ len + 3 ];
  
      this._riotx_change_handlers.push({
        store: store,
        evtName: evtName,
        handler: handler
      });
      args.unshift(handler);
      args.unshift(evtName);
      store.change.apply(store, args);
    }
docs: add and keep event listener for store changes. through this function the event listeners will be unbinded automatically.