code: def test_clean_names_enforce_str():
      """Test enforce_strings on non string columns"""
      df = pd.DataFrame({1: [3, 4], 11: [5, 6]})
      outcome = df.clean_names().columns.tolist()
      assert outcome == ["1", "11"]
  
file_path: pyjanitor/tests/functions/test_clean_names.py
imports: import pandas
  import pytest
  from janitor.errors import JanitorError
label_desc: Use image node_id 17 for calling a global function with example usage: test_clean_names_enforce_str() without return types