code: func (w *Worker) PreAccountAddBalance(job *data.Job) error {
  	logger := w.logger.Add("method", "PreAccountAddBalance", "job", job)
  
  	acc, err := w.relatedAccount(logger, job, data.JobPreAccountAddBalance)
  	if err != nil {
  		return err
  	}
  
  	jobData, err := w.approvedBalanceData(logger, job)
  	if err != nil {
  		return err
  	}
  
  	key, err := w.key(logger, acc.PrivateKey)
  	if err != nil {
  		return err
  	}
  
  	auth := bind.NewKeyedTransactor(key)
  	auth.GasLimit = w.gasConf.PSC.AddBalanceERC20
  	auth.GasPrice = new(big.Int).SetUint64(jobData.GasPrice)
  	tx, err := w.ethBack.PSCAddBalanceERC20(auth, uint64(jobData.Amount))
  	if err != nil {
  		logger.Error(err.Error())
  		return ErrPSCAddBalance
  	}
  
  	return w.saveEthTX(logger, job, tx, "PSCAddBalanceERC20", job.RelatedType,
  		job.RelatedID, acc.EthAddr, data.HexFromBytes(w.pscAddr.Bytes()))
  }
docs: // PreAccountAddBalance adds balance to psc.