docs: function Engine(ops) {
  		this.amsu = new angularMultiSelectUtils();
  		_extends(this, this.amsu.sanitize_ops(ops));
  
  		/*
     * Initiate the database and setup index fields.
     */
  		this.db = new loki();
  
  		this.on_data_change_fn = null;
  		this.on_visual_change_fn = null;
  	}