code: def test_dataset_feature_with_none(feature):
      data = {"col": [None]}
      features = Features({"col": feature})
      dset = Dataset.from_dict(data, features=features)
      item = dset[0]
      assert item.keys() == {"col"}
      assert item["col"] is None
      batch = dset[:1]
      assert len(batch) == 1
      assert batch.keys() == {"col"}
      assert isinstance(batch["col"], list) and all(
          item is None for item in batch["col"]
      )
      column = dset["col"]
      assert len(column) == 1
      assert isinstance(column, list) and all(
          item is None for item in column
      )
  
      # nested tests
  
      data = {"col": [[None]]}
      features = Features({"col": Sequence(feature)})
      dset = Dataset.from_dict(data, features=features)
      item = dset[0]
      assert item.keys() == {"col"}
      assert all(i is None for i in item["col"])
  
      data = {"nested": [{"col": None}]}
      features = Features({"nested": {"col": feature}})
      dset = Dataset.from_dict(data, features=features)
      item = dset[0]
      assert item.keys() == {"nested"}
      assert item["nested"].keys() == {"col"}
      assert item["nested"]["col"] is None
  
imports: import datetime
  from unittest import TestCase
  from unittest.mock import patch
  import numpy
  import pandas
  import pyarrow
  import pytest
  from datasets import Array2D
  from datasets.arrow_dataset import Dataset
  from datasets.features import Audio, ClassLabel, Features, Image, Sequence, Value
  from datasets.features.features import _arrow_to_datasets_dtype, _cast_to_python_objects, cast_to_python_objects, encode_nested_example, generate_from_dict, string_to_arrow
  from datasets.features.translation import Translation, TranslationVariableLanguages
  from datasets.info import DatasetInfo
  from datasets.utils.py_utils import asdict
  from ..utils import require_jax, require_tf, require_torch
label_desc: Use image node_id 8 for calling a global function with example usage: test_dataset_feature_with_none(feature) without return types