//@RightBack
function rightBack(sourceStr, keyStr){
	arr = sourceStr.split(keyStr);
	return (sourceStr.indexOf(keyStr) == -1 | keyStr=='') ? '' : arr.pop()
}

//@LeftBack
function leftBack(sourceStr, keyStr){
	arr = sourceStr.split(keyStr)
	arr.pop();
	return (keyStr==null | keyStr=='') ? '' : arr.join(keyStr)
}