std::string decodeUnicodeEscapeSequences(const std::string& input) {
    std::regex pattern("\\\\u([0-9A-Fa-f]{4})");
    std::string output;
    std::smatch match;

    auto pos = input.cbegin();
    while (std::regex_search(pos, input.cend(), match, pattern)) {
        output += match.prefix().str();
        auto codepoint = std::stoi(match[1], nullptr, 16);
        output += static_cast<char>((codepoint >> 12) | 0xE0);
        output += static_cast<char>(((codepoint >> 6) & 0x3F) | 0x80);
        output += static_cast<char>((codepoint & 0x3F) | 0x80);
        pos = match.suffix().first;
    }
    output += std::string(pos, input.cend());
    return output;
}