function is_in_array with deep search

<?php
/**
 * Author: Peter Dragicevic [peter-91@hotmail.de]
 * Authors-Website: http://petschko.org/
 * Licence: http://creativecommons.org/licenses/by-sa/4.0/
 * Date: 28.07.2015
 * Time: 09:36
 */

/**
 * @param mixed $subject - needle
 * @param array $array - haystack
 * @param bool $deep_search - search subarrays too
 * @return bool - true if found
 */
function is_in_array($subject, $array, $deep_search = false) {
    if(! $subject)
        return false;

    foreach($array as $string) {
        if(is_array($string) && $deep_search)
            if(is_in_array($subject, $string, true))
                return true;
        if($string == $subject)
            return true;
    }

    return false;
}

?>