How to use the textstat.textstat.textstat.difficult_words function in textstat

def get_feat_readability_metrics(self):
        # https://github.com/shivam5992/textstat

        try:
            test_data = self.webscrap.get_body()
            out = []
            out.append(textstat.flesch_reading_ease(test_data))
            out.append(textstat.smog_index(test_data))
            out.append(textstat.flesch_kincaid_grade(test_data))
            out.append(textstat.coleman_liau_index(test_data))
            out.append(textstat.automated_readability_index(test_data))
            out.append(textstat.dale_chall_readability_score(test_data))
            out.append(textstat.difficult_words(test_data))
            out.append(textstat.linsear_write_formula(test_data))
            out.append(textstat.gunning_fog(test_data))
            #out.append(textstat.text_standard(test_data))
            return out, False

        except Exception as e:
            config.logger.error(repr(e))
            return MISSING_FEATURE * 9, True