code: def test_empty_struct() -> None:
      # List<struct>
      df = pl.DataFrame({"a": [[{}]]})
      assert df.to_dict(as_series=False) == {"a": [[{"": None}]]}
  
      # Struct one not empty
      df = pl.DataFrame({"a": [[{}, {"a": 10}]]})
      assert df.to_dict(as_series=False) == {
          "a": [[{"a": None}, {"a": 10}]]
      }
  
      # Empty struct
      df = pl.DataFrame({"a": [{}]})
      assert df.to_dict(as_series=False) == {"a": [{"": None}]}
  
imports: from __future__ import annotations
  from dataclasses import dataclass
  from datetime import datetime, time
  from typing import TYPE_CHECKING
  import pandas
  import pyarrow
  import pytest
  import polars
  import polars.selectors
  from polars.testing import assert_frame_equal, assert_series_equal
label_desc: Use image node_id 34 for calling a global function with example usage: test_empty_struct() without return types