code: def test_functional_transform(dataset_adapter):
      assert next(iter(dataset_adapter)).is_directed()
      dataset_adapter = dataset_adapter.to_undirected()
      assert next(iter(dataset_adapter)).is_undirected()
  
file_path: pytorch_geometric/test/data/test_datapipes.py
imports: import pytest
  import torch
  from torch_geometric.data import Data
  from torch_geometric.data.datapipes import DatasetAdapter
  from torch_geometric.loader import DataLoader
  from torch_geometric.testing import withPackage
  from torch_geometric.utils import to_smiles
label_desc: Use image node_id 4 for calling a global function with example usage: test_functional_transform(dataset_adapter) without return types