static public function mid($str, $start, $howManyChars = 0) 
    {
        $start--;
        if((int)$howManyChars === 0) {
            $howManyChars = (int)strlen($str) - (int)$start;
        }

        return (string)substr($str, (int)$start, (int)$howManyChars);
    }