public abstract int convert(ref convert_input input, out convert_result result);
public static int convert(ref convert_input input, out convert_result result) => _impl.convert(ref input, out result);
private static extern int pcrenet_convert(ref convert_input input, out convert_result result);
public override int convert(ref convert_input input, out convert_result result) => pcrenet_convert(ref input, out result);