code: func decimal2RoundUint(x *MyDecimal) (uint64, error) {
  	roundX := new(MyDecimal)
  	x.Round(roundX, 0)
  	var (
  		uintX uint64
  		err   error
  	)
  	if roundX.IsNegative() {
  		intX, err := roundX.ToInt()
  		if err != nil && err != ErrTruncated {
  			return 0, errors.Trace(err)
  		}
  		uintX = uint64(intX)
  	} else {
  		uintX, err = roundX.ToUint()
  		if err != nil && err != ErrTruncated {
  			return 0, errors.Trace(err)
  		}
  	}
  
  	return uintX, nil
  }
docs: // decimal2RoundUint converts a MyDecimal to an uint64 after rounding.