code: def clean_df(df, header=None, **read_csv_kwargs):
      
      df = read_csv(df, header=header, **read_csv_kwargs)
      df = df.fillna(' ')
      for col in df.columns:
          df[col] = df[col].apply(unicode2ascii)
      return df
docs: Convert UTF8 characters in a CSV file or dataframe into ASCII
  
      Args:
        df (DataFrame or str): DataFrame or path or url to CSV