public static function parseArray(array $values) {

        // Initialize the output.
        $output = [];

        // Handle each value.
        foreach ($values as $key => $value) {

            // Check if the value is null.
            if (null === $value) {
                continue;
            }

            // Check if the value is an array.
            if (true === is_array($value)) {
                $buffer = trim(implode(" ", $value));
            } else {
                $buffer = trim($value);
            }

            // Check if the buffer is not empty.
            if ("" !== $buffer) {
                $output[] = $key . "=\"" . preg_replace("/\s+/", " ", $buffer) . "\"";
            }
        }

        // Concatenates all attributes.
        return implode(" ", $output);
    }