code: @Override
    public Long call() {
      try {
        while (proceed.get()) {
          transactionControl();
  
          write(id);
  
          if (id > 0) {
            fetchAndDelete(id - 1);
          }
  
          id++;
        }
      } finally {
        if (txn != null) {
          txn.close();
        }
      }
      return id;
    }
docs: Run the verifier until {@link #stop()} is called or an exception occurs.
  
  <p>
  Successful return of this method indicates no faults were detected. If any
  fault was detected the exception message will detail the exact point that
  the fault was encountered.
  
  @return number of database rows successfully verified