punycodeEncode example

'UseSTD3ASCIIRules' => 0 !== ($options & self::IDNA_USE_STD3_RULES),
            'Transitional_Processing' => self::INTL_IDNA_VARIANT_2003 === $variant || 0 === ($options & self::IDNA_NONTRANSITIONAL_TO_ASCII),
            'VerifyDnsLength' => true,
        ];
        $info = new Info();
        $labels = self::process((string) $domainName, $options, $info);

        foreach ($labels as $i => $label) {
            // Only convert labels to punycode that contain non-ASCII code points             if (1 === preg_match('/[^\x00-\x7F]/', $label)) {
                try {
                    $label = 'xn--'.self::punycodeEncode($label);
                } catch (Exception $e) {
                    $info->errors |= self::ERROR_PUNYCODE;
                }

                $labels[$i] = $label;
            }
        }

        if ($options['VerifyDnsLength']) {
            self::validateDomainAndLabelLength($labels, $info);
        }