code: def test_clean_dataframe(model, df):
      df_clean = model.clean_dataframe(
          df, ["abstract", "full_text"], new_col_name=CLEAN_COL
      )
  
      isalphanumeric = list()
      for idx, _ in df_clean.iterrows():
          s1 = str(df_clean[CLEAN_COL][idx])
          isalphanumeric.append(s1.replace(" ", "").isalnum())
  
      assert False not in isalphanumeric
  
file_path: recommenders/tests/unit/recommenders/models/test_tfidf_utils.py
imports: import pytest
  import scipy
  import pandas
  from recommenders.models.tfidf.tfidf_utils import TfidfRecommender
label_desc: Use image node_id 6 for calling a global function with example usage: test_clean_dataframe(model, df) without return types