class_docstr: Mock downloading a single file.
class_docstr_tok: ["Mock","downloading","a","single","file","."]
code: def __init__(self, cache_root: str):
      super().__init__(url=..., name=..., cache_root=cache_root)
  
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 MockSingleTabbedDataset object from inherited base classes: SingleTabbedDataset with example: obj = MockSingleTabbedDataset(cache_root)