code: func IsLowS(k *ecdsa.PublicKey, s *big.Int) (bool, error) {
  	halfOrder, ok := curveHalfOrders[k.Curve]
  	if !ok {
  		return false, fmt.Errorf("curve not recognized [%s]", k.Curve)
  	}
  
  	return s.Cmp(halfOrder) != 1, nil
  
  }
docs: // IsLow checks that s is a low-S