Question: what episode does lex luthor return in smallville
[{'answer': 'the series finale', 'provenance': [{'wikipedia_id': '17553330', 'title': 'Lex Luthor (Smallville)', 'start_paragraph_id': 16, 'start_character': 1501, 'end_paragraph_id': 16, 'end_character': 1518, 'bleu_score': 1.0, 'section': 'Section::::Portrayal.\n'}]}, {'provenance': [{'wikipedia_id': '17553330', 'title': 'Lex Luthor (Smallville)', 'start_paragraph_id': 16, 'start_character': 0, 'end_paragraph_id': 16, 'end_character': 1685, 'bleu_score': 0.9931152160837011, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 12468528190518065700}, 'section': 'Section::::Portrayal.\n'}]}]