code: private Table summarize(TableSliceGroup group) {
          List<Table> results = new ArrayList<>();
  
          ArrayListMultimap<String, AggregateFunction<?, ?>> reductionMultimap = getAggregateFunctionMultimap();
  
          for (String name : reductionMultimap.keys()) {
              List<AggregateFunction<?, ?>> reductions = reductionMultimap.get(name);
              results.add(group.aggregate(name, reductions.toArray(new AggregateFunction<?, ?>[0])));
          }
          return combineTables(results);
      }
docs: Associates the columns to be summarized with the functions that match their type. All valid combinations are used
  @param group A table slice group
  @return      A table containing a row of summarized data for each group in the table slice group