code: func (s EIP155Signer) SignatureValues(tx *Transaction, sig []byte) (R, S, V *big.Int, err error) {
  	R, S, V, err = HomesteadSigner{}.SignatureValues(tx, sig)
  	if err != nil {
  		return nil, nil, nil, err
  	}
  	if s.chainId.Sign() != 0 {
  		V = big.NewInt(int64(sig[64] + 35))
  		V.Add(V, s.chainIdMul)
  	}
  	return R, S, V, nil
  }
docs: // SignatureValues returns signature values. This signature
  // needs to be in the [R || S || V] format where V is 0 or 1.