PHP: get last business day

LastBusinessDay.php

<?php   
/**
 * @param bool $with_today
 * @return DateTime Last business day
 */
function lastBusinessDay($with_today = false): DateTime
{
    $date = new DateTime();

    if (!$with_today) {
        $date->sub(new DateInterval('P1D')); // yesterday
    }

    $w = $date->format('w');

    if ($w >= 1 && $w <= 5) { // between Mon-Fri
        return $date;
    }

    return new DateTime('last friday');
}