docs: public static void addTSDBFunctions(final TSDB tsdb) {
      available_functions.put("divideSeries", new DivideSeries(tsdb));
      available_functions.put("divide", new DivideSeries(tsdb));
      available_functions.put("sumSeries", new SumSeries(tsdb));
      available_functions.put("sum", new SumSeries(tsdb));
      available_functions.put("diffSeries", new DiffSeries(tsdb));
      available_functions.put("difference", new DiffSeries(tsdb));
      available_functions.put("multiplySeries", new MultiplySeries(tsdb));
      available_functions.put("multiply", new MultiplySeries(tsdb));
    }