Online PHP editor | refs for FtTUh

<?php $input = array( "name" => array("type" => "text", "null" => "NOT NULL"), "email" => array("type" => "text", "null" => "NOT NULL"), "tel" => array("type" => "text", "null" => "NOT NULL"), "warehouse" => array("type" => "text", "null" => "NOT NULL"), ); echo implode(', ', array_map(function ($k, $entry) { return $k; }, $input));