code: def test_at_timezone():
      # https://github.com/pandas-dev/pandas/issues/33544
      result = DataFrame({"foo": [datetime(2000, 1, 1)]})
      with tm.assert_produces_warning(
          FutureWarning, match="incompatible dtype"
      ):
          result.at[0, "foo"] = datetime(
              2000, 1, 2, tzinfo=timezone.utc
          )
      expected = DataFrame(
          {"foo": [datetime(2000, 1, 2, tzinfo=timezone.utc)]},
          dtype=object,
      )
      tm.assert_frame_equal(result, expected)
  
imports: from datetime import datetime, timezone
  import numpy
  import pytest
  from pandas.errors import InvalidIndexError
  from pandas import CategoricalDtype, CategoricalIndex, DataFrame, DatetimeIndex, Index, MultiIndex, Series, Timestamp
  import pandas._testing
label_desc: Use image node_id 1 for calling a global function with example usage: test_at_timezone() without return types