docs: function DragTabs($el, options) {
    // we are an event emitter
    assign(this, createEmitter());
  
    this.options = options || {};
    this.$el = $el;
  
    this._moveTab = bind(this._moveTab, this);
  
    this._onDragstart = bind(this._onDragstart, this);
    this._onDragend = bind(this._onDragend, this);
    this._onDrop = bind(this._onDrop, this);
  
    this._init();
  
    this.update();
  }