code: def _check_dataset_exists(dataset_configs):
      assert "dataset_name" in dataset_configs, (
          "Must specify dataset_name in " "dataset_configs."
      )
      dataset_name = dataset_configs["dataset_name"]
      assert (
          dataset_configs["dataset_name"] in DATASET_INFO
      ), f"{dataset_name} is not supported."
      return dataset_name
  
file_path: scenic/scenic/projects/robust_segvit/datasets/cityscapes_variants.py
imports: import functools
  from typing import Optional
  from absl import logging
  from flax import jax_utils
  import jax.numpy
  from scenic.dataset_lib import cityscapes_dataset
  from scenic.dataset_lib import dataset_utils
  from scenic.dataset_lib import datasets
  import tensorflow
  import tensorflow_datasets
label_desc: Use image node_id 4 for calling a global function with example usage: _check_dataset_exists(dataset_configs) and returns: dataset_name