code: def setUpClass(cls):
      super(OpusTestCustomConfigTest, cls).setUpClass()
  
      config = opus_dataset_builder.OpusConfig(
          version=tfds.core.Version("0.1.0"),
          language_pair=("de", "en"),
          subsets=["Tanzil", "EMEA"],
      )
      opus_dataset_builder.Builder.BUILDER_CONFIGS = [config]
  
imports: from tensorflow_datasets import testing
  from tensorflow_datasets.datasets.opus import opus_dataset_builder
  import tensorflow_datasets.public_api
label_desc: Use image node_id 1 for calling the OpusTestCustomConfigTest obj's underlying member method code with example usage: obj.setUpClass(cls) without return types