class_docstr: Mock downloading a tar.gz archive with three pre-stratified files.
class_docstr_tok: ["Mock","downloading","a","tar.gz","archive","with","three","pre-stratified","files","."]
code: def __init__(self, cache_root: str):
      super().__init__(
          url=constants.RESOURCES.joinpath("nations.tar.gz").as_uri(),
          cache_root=cache_root,
          relative_testing_path=pathlib.PurePath("nations", "test.txt"),
          relative_training_path=pathlib.PurePath(
              "nations", "train.txt"
          ),
          relative_validation_path=pathlib.PurePath(
              "nations", "valid.txt"
          ),
      )
  
imports: import pathlib
  import unittest
  from io import BytesIO
  from urllib.request import urlopen
  from pykeen.datasets import Kinships, Nations, dataset_resolver
  from pykeen.datasets.base import PackedZipRemoteDataset, SingleTabbedDataset, TarFileRemoteDataset, TarFileSingleDataset, UnpackedRemoteDataset
  from pykeen.datasets.nations import NATIONS_TEST_PATH, NATIONS_TRAIN_PATH, NATIONS_VALIDATE_PATH
  from tests import cases, constants
label_desc: Use image node_id 1 to create a new MockTarFileRemoteDataset object from inherited base classes: TarFileRemoteDataset with example: obj = MockTarFileRemoteDataset(cache_root)