code: def test_count_mixed_object():
      ser = Series(
          [
              "a",
              np.nan,
              "b",
              True,
              datetime.today(),
              "foo",
              None,
              1,
              2.0,
          ],
          dtype=object,
      )
      result = ser.str.count("a")
      expected = Series(
          [1, np.nan, 0, np.nan, np.nan, 0, np.nan, np.nan, np.nan]
      )
      tm.assert_series_equal(result, expected)
  
imports: from datetime import datetime, timedelta
  import numpy
  import pytest
  from pandas import DataFrame, Index, MultiIndex, Series
  import pandas._testing
  from pandas.core.strings.accessor import StringMethods
  from pandas.tests.strings import object_pyarrow_numpy
label_desc: Use image node_id 4 for calling a global function with example usage: test_count_mixed_object() without return types