untested preg_match for valid time

isValidTime.php

<?php 
public function isValidTime($time,$is24Hours=true,$seconds=false) {
            $pattern = "/^".($is24Hours ? "([1-2][0-3]|[01]?[1-9])" : "(1[0-2]|0?[1-9])").":([0-5]?[0-9])".($seconds ? ":([0-5]?[0-9])" : "")."$/";
            if (preg_match($pattern, $time)) {
                return true;
            }
            return false;
        }