private static function _prepareQuestionString($input)
    {
        $regex = '';
        if (is_array($input) === true) {
            $regex = '^';
            $start = true;
            foreach ($input as $row) {
                if ($start === false) {
                    $regex .= '|';
                }

                $start  = false;
                $regex .= '(';
                $one    = null;
                if (strlen($row) > 2) {
                    $one = true;
                }

                foreach (str_split($row, 1) as $char) {
                    $regex .= '[' . $char;
                    $regex .= strtoupper($char) . ']';
                    if ($one === true) {
                        $one    = false;
                        $regex .= '(';
                    }
                }

                if ($one === false) {
                    $regex .= ')';
                }

                $regex .= '?)';
            }
        }

        return $regex;
    }