code: function(id_field, event_args) {
  
  		var id = event_args.record.get('id');
  		if (id in this._records_by_id) Lava.t("Duplicate record id in module " + this._name);
  		this._records_by_id[id] = event_args.record;
  
  	}
docs: Record's ID has been created (ID fields never change). Need to update local `_records_by_id` hash
  @param {Lava.data.field.Abstract} id_field
  @param {Lava.data.field.Abstract#event:changed} event_args