Question: how many episodes are there in season 1 of supergirl
[{'answer': '20', 'provenance': [{'wikipedia_id': '47607880', 'title': 'List of Supergirl episodes', 'start_paragraph_id': 1, 'start_character': 281, 'end_paragraph_id': 1, 'end_character': 283, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]