code: def test_transform_mixed_column_name_dtypes():
      # GH39025
      df = DataFrame({"a": ["1"]})
      msg = r"Column\(s\) \[1, 'b'\] do not exist"
      with pytest.raises(KeyError, match=msg):
          df.transform({"a": int, 1: str, "b": int})
  
imports: from itertools import chain
  import re
  import numpy
  import pytest
  from pandas.errors import SpecificationError
  from pandas import DataFrame, Series, date_range
  import pandas._testing
label_desc: Use image node_id 11 for calling a global function with example usage: test_transform_mixed_column_name_dtypes() without return types