code: def test_struct_hashes() -> None:
      dtypes = (
          pl.Struct,
          pl.Struct([pl.Field("a", pl.Int64)]),
          pl.Struct(
              [
                  pl.Field("a", pl.Int64),
                  pl.Field("b", pl.List(pl.Int64)),
              ]
          ),
      )
      assert len({hash(tp) for tp in (dtypes)}) == 3
  
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 5 for calling a global function with example usage: test_struct_hashes() without return types