class_docstr: Base class for loading datasets.
  
  Note that you should never instantiate the :class:`Dataset` class directly
  (same goes for its derived classes), but instead use one of the three
  available methods for loading datasets.
code: def construct_testset(self, raw_testset):
      return [
          (ruid, riid, r_ui_trans)
          for (ruid, riid, r_ui_trans, _) in raw_testset
      ]
  
imports: import itertools
  import os
  import sys
  from collections import defaultdict
  from .builtin_datasets import BUILTIN_DATASETS, download_builtin_dataset
  from .reader import Reader
  from .trainset import Trainset
label_desc: Use image node_id 8 for calling the Dataset obj's underlying member method code with example usage: obj.construct_testset(raw_testset) and returns: unknown