function keyByCallback( prop ) {
	return onValue;

	/**
	* Returns a value assigned to a specified property.
	*
	* @private
	* @param {Object} value - collection value
	* @returns {string} property value
	*/
	function onValue( value ) {
		return value[ prop ];
	}
}
/**
* Returns a callback which returns a value assigned to a specified property.
*
* @private
* @param {string} prop - property name
* @returns {Function} callback
*/
Returns a callback which returns a value assigned to a specified property.
Returns a callback which returns a value assigned to a specified property .
function keyByCallback( prop ) {
	return onValue;
	function onValue( value ) {
		return value[ prop ];
	}
}
function keyByCallback ( prop ) { return onValue ; function onValue ( value ) { return value [ prop ] ; } }
Returns a callback which returns a value assigned to a specified property.
Returns a callback which returns a value assigned to a specified property .
/**
	* Returns a value assigned to a specified property.
	*
	* @private
	* @param {Object} value - collection value
	* @returns {string} property value
	*/