def test_get_standardized_and_normalized_df(self):
     data_getter = DataGetter()
     df_result = data_getter.get_standardized_and_normalized_df()
     self.assertIsInstance(
         df_result, pd.DataFrame,
         "There was an issue with standardization and normalization.")
     df_result.to_excel("../output/df_norm_std.xlsx")