code: protected void writeTupleGenerator( String function, TupleGenerator generator)
      {
      Long seed = generator.getRandomSeed();
      
      writer_
        .element( TUPLEGENERATOR_TAG)
        .attribute( FUNCTION_ATR, function)
        .attributeIf( seed != null, SEED_ATR, String.valueOf( seed))
        .attribute( TUPLES_ATR, String.valueOf( generator.getDefaultTupleSize()))
        .contentIf(
          !generator.getCombiners().isEmpty(),
          () -> generator.getCombiners().stream().forEach( combiner -> writeCombiner( combiner)))
        .write();
      }
docs: Writes the given generator definition.