code: def test_cast(self):
      dset = self._create_dummy_dataset_dict(multiple_columns=True)
      features = dset["train"].features
      features["col_1"] = Value("float64")
      dset = dset.cast(features)
      for dset_split in dset.values():
          self.assertEqual(dset_split.num_columns, 2)
          self.assertEqual(
              dset_split.features["col_1"], Value("float64")
          )
          self.assertIsInstance(dset_split[0]["col_1"], float)
      del dset
  
imports: import os
  import tempfile
  from unittest import TestCase
  import numpy
  import pandas
  import pytest
  from datasets import load_from_disk
  from datasets.arrow_dataset import Dataset
  from datasets.dataset_dict import DatasetDict, IterableDatasetDict
  from datasets.features import ClassLabel, Features, Sequence, Value
  from datasets.iterable_dataset import IterableDataset
  from datasets.splits import NamedSplit
  from .utils import assert_arrow_memory_doesnt_increase, assert_arrow_memory_increases, require_tf, require_torch
label_desc: Use image node_id 13 for calling the DatasetDictTest obj's underlying member method code with example usage: obj.test_cast() without return types