code: func (tx *Transaction) Hash() common.Hash {
  	if hash := tx.hash.Load(); hash != nil {
  		return hash.(common.Hash)
  	}
  	v := rlpHash(tx)
  	tx.hash.Store(v)
  	return v
  }
docs: // Hash hashes the RLP encoding of tx.
  // It uniquely identifies the transaction.