Question: what is season 3 of american horror story about
[{'answer': 'a Coven of Salem witches'}, {'provenance': [{'wikipedia_id': '38827962', 'title': 'American Horror Story: Coven', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 386, 'bleu_score': 0.788639149524725, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 18152022095542137700}, 'section': 'Section::::Abstract.'}]}]