code: function() {
      this._unbindModel();
      this.map.bind('change:view_bounds_sw',  this._changeBounds, this);
      this.map.bind('change:view_bounds_ne',  this._changeBounds, this);
      this.map.bind('change:zoom',            this._setZoom, this);
      this.map.bind('change:scrollwheel',     this._setScrollWheel, this);
      this.map.bind('change:keyboard',        this._setKeyboard, this);
      this.map.bind('change:center',          this._setCenter, this);
      this.map.bind('change:attribution',     this.setAttribution, this);
    }
docs: bind model properties