env function taken from https://github.com/modess/deploying-php-applications

env-function.php

<?php

function env($key, $default = null)
{
    $value = getenv($key);

    if ($value === false) {
        return value($default);
    }
    
    switch (strtolower($value)) {
        case 'true':
        case '(true)':
            return true;
        case 'false':
        case '(false)':
            return false;
        case 'empty':
        case '(empty)':
            return '';
        case 'null':
        case '(null)':
            return;
    }

    return $value;
}