docs: @Override
      public String writeSingle(String key) throws Exception {
          MutationBatch m = keyspace.prepareMutationBatch().withConsistencyLevel(ConsistencyLevel.valueOf(config.getWriteConsistencyLevel()));
  
          ColumnListMutation<Integer> colsMutation = m.withRow(this.CF, key);
  
          for (int i = 0; i < config.getColsPerRow(); i++) {
              colsMutation.putColumn(i, dataGenerator.getRandomValue());
          }
  
          m.execute();
  
          return ResultOK;
      }