/// $PackageInfo: require_system("darwin") pkg-config tre
/// $PackageInfo: require_system("debian") libtre-dev pkg-config
/// $PackageInfo: require_system("ubuntu") libtre-dev pkg-config
/// $PackageInfo: require_system("darwin") pkg-config tre
/// $PackageInfo: require_system("debian") libtre-dev pkg-config
/// $PackageInfo: require_system("ubuntu") libtre-dev pkg-config