code: public int consume(Map<String, String> initialVars) {
          if (isExit()) {
              return 0;
          }
  
          currentLineCount++;
          currentRow++;
          return super.consume(initialVars);
      }
docs: Consume a data set (Map of Variable names and their Values)
  
  @param initialVars a map containing the initial variables assignments
  @return Number of rows written; 0 rows if exiting 1 row otherwise