code: def clean_worksheet(wks, gfile_id, wks_name, credentials):
      
  
      values = wks.get_all_values()
      if values:
          df_ = pd.DataFrame(index=range(len(values)),
                             columns=range(len(values[0])))
          df_ = df_.fillna('')
          wks = upload(df_, gfile_id, wks_name=wks_name,
                       col_names=False, row_names=False, clean=False,
                       credentials=credentials)
      return wks
docs: DOCS...