<?php
function is_federal_holiday(DateTime $date){
	$year = $date->format('Y');
	$federal_holidays = array_map(function($date_string) use($year){
		$date = new DateTime($date_string . ' ' . $year);
		if ($date->format('l') === 'Saturday') $date->modify('-1 day');
		if ($date->format('l') === 'Sunday') $date->modify('+1 day');
		return $date;
	}, [
		"january 1",                    //new year's day
		"third monday of january",      //martin luther king, jr. day
		"third monday of february",     //george washington’s birthday
		"last monday of may",           //memorial day
		"july 4",                       //independence day
		"first monday of september",    //labor day
		"second monday of october",     //columbus day
		"november 11",                  //veterans day
		"fourth thursday of november",  //thanksgiving day
		"december 25",                  //christmas day
	]);
	return array_filter($federal_holidays, function($federal_holiday) use($date){
		return $federal_holiday == $date;
	});
}