Time travel (PHP)

time_travel.php

/**
 * Time Travel returns dates in the past or the future, to a specific format, based on a seed date.
 * 
 * @param $date_format the format of dates (seed and returned)
 * @param $date the seed date
 * @param $where_to time travel "step" in days (e.g. for yesterday "-1", tomorrow "+1" and so forth) 
 */  
function time_travel( $date_format, $date, $where_to ) {
	return date( $date_format, strtotime( $date . ' ' . $where_to . ' day' ) );
}