code: def test_names_sep_typeerror(df_checks):
      """Raise TypeError if names_sep is a wrong type."""
      with pytest.raises(
          TypeError, match="names_sep should be one of.+"
      ):
          df_checks.explode_index(axis="columns", names_sep=1)
  
file_path: pyjanitor/tests/functions/test_explode_index.py
imports: import pandas
  import pytest
  from pandas.testing import assert_frame_equal
label_desc: Use image node_id 7 for calling a global function with example usage: test_names_sep_typeerror(df_checks) without return types