code: def df_duplicated_columns():
      data = {
          "a": range(10),
          "b": range(10),
          "A": range(10, 20),
          "a*": range(20, 30),
      }
      df = pd.DataFrame(data)
      # containing three 'a' columns being duplicated
      clean_df = df.clean_names(remove_special=True)
      return clean_df
  
file_path: pyjanitor/tests/conftest.py
imports: import os
  import numpy
  import pandas
  import pytest
  from janitor.testing_utils import date_data
label_desc: Use image node_id 11 for calling a global function with example usage: df_duplicated_columns() and returns: clean_df