code: function key() {
  	var hashName = _.result( this, 'hashAttribute' ) || _.result( this, 'idAttribute' ),
  		rangeNake = _.result( this, 'rangeAttribute' );
  
  	return this.pick( hashName, rangeNake );
  }
docs: Convenience method to get the key attribute(s) (hash and/or range) of a model.
  To call this method use: key.call( model )