private function tokensToString(array $tokens): string
    {
        $lineCount = 0;
        $headerLines = [];
        $headerLines[] = $this->name.': ';
        $currentLine = &$headerLines[$lineCount++];

        // Build all tokens back into compliant header
        foreach ($tokens as $i => $token) {
            // Line longer than specified maximum or token was just a new line
            if (("\r\n" === $token) ||
                ($i > 0 && \strlen($currentLine.$token) > $this->lineLength)
                && 0 < \strlen($currentLine)) {
                $headerLines[] = '';
                $currentLine = &$headerLines[$lineCount++];
            }

            // Append token to the line
            if ("\r\n" !== $token) {
                $currentLine .= $token;
            }
        }

        // Implode with FWS (RFC 2822, 2.2.3)
        return implode("\r\n", $headerLines);
    }