private function getIndentAt(Tokens $tokens, $index)
    {
        $content = '';
        $lineEnding = $this->whitespacesConfig->getLineEnding();

        // find line ending token
        for ($index; $index > 0; --$index) {
            if (false !== strstr($tokens[$index]->getContent(), $lineEnding)) {
                break;
            }
        }

        if ($tokens[$index]->isWhitespace()) {
            $content = $tokens[$index]->getContent();
            --$index;
        }

        if ($tokens[$index]->isGivenKind(T_OPEN_TAG)) {
            $content = $tokens[$index]->getContent().$content;
        }

        if (1 === Preg::match('/\R{1}([ \t]*)$/', $content, $matches)) {
            return $matches[1];
        }

        return null;
    }
private function getIndentAt(Tokens $tokens, $index)
    {
        $content = '';
        $lineEnding = $this->whitespacesConfig->getLineEnding();

        // find line ending token
        for ($index; $index > 0; --$index) {
            if (false !== strstr($tokens[$index]->getContent(), $lineEnding)) {
                break;
            }
        }

        if ($tokens[$index]->isWhitespace()) {
            $content = $tokens[$index]->getContent();
            --$index;
        }

        if ($tokens[$index]->isGivenKind(T_OPEN_TAG)) {
            $content = $tokens[$index]->getContent().$content;
        }

        if (1 === Preg::match('/\R{1}([ \t]*)$/', $content, $matches)) {
            return $matches[1];
        }

        return null;
    }
@param int $index

@return null|string