public async Task <string> AddAsync(int a, int b, CancellationToken cancellationToken = default)
{
var r = await _calcService.AddAsync(a, b, cancellationToken);
return(Math.Abs(r) != r ? "-" : "" + await _toRomanService.ToRomanAsync((ushort)Math.Abs(r), cancellationToken));
}
