Question: how many types of ion channels are there
[{'answer': 'over 300', 'provenance': [{'wikipedia_id': '15303', 'title': 'Ion channel', 'start_paragraph_id': 12, 'start_character': 10, 'end_paragraph_id': 12, 'end_character': 18, 'bleu_score': 1.0, 'section': 'Section::::Diversity.\n'}]}, {'provenance': [{'wikipedia_id': '15303', 'title': 'Ion channel', 'start_paragraph_id': 12, 'start_character': 0, 'end_paragraph_id': 12, 'end_character': 244, 'bleu_score': 0.955027111100031, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 14896686936369716962}, 'section': 'Section::::Diversity.\n'}]}]