code: func (ec *EthereumClient) GetNonceAt(ctx *Context, account *Address, number int64) (nonce int64, _ error) {
  	if number < 0 {
  		rawNonce, err := ec.client.NonceAt(ctx.context, account.address, nil)
  		return int64(rawNonce), err
  	}
  	rawNonce, err := ec.client.NonceAt(ctx.context, account.address, big.NewInt(number))
  	return int64(rawNonce), err
  }
docs: // GetNonceAt returns the account nonce of the given account.
  // The block number can be <0, in which case the nonce is taken from the latest known block.