Question: how many models of mac computers does apple produce
[{'answer': 'iMac', 'provenance': [{'wikipedia_id': '19006979', 'title': 'Macintosh', 'start_paragraph_id': 4, 'start_character': 240, 'end_paragraph_id': 4, 'end_character': 244, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'answer': 'Mac Mini', 'provenance': [{'wikipedia_id': '19006979', 'title': 'Macintosh', 'start_paragraph_id': 4, 'start_character': 793, 'end_paragraph_id': 4, 'end_character': 801, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'answer': 'Mac Pro', 'provenance': [{'wikipedia_id': '19006979', 'title': 'Macintosh', 'start_paragraph_id': 4, 'start_character': 768, 'end_paragraph_id': 4, 'end_character': 775, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'answer': 'MacBook', 'provenance': [{'wikipedia_id': '19006979', 'title': 'Macintosh', 'start_paragraph_id': 4, 'start_character': 837, 'end_paragraph_id': 4, 'end_character': 844, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'answer': 'MacBook Air', 'provenance': [{'wikipedia_id': '19006979', 'title': 'Macintosh', 'start_paragraph_id': 4, 'start_character': 837, 'end_paragraph_id': 4, 'end_character': 848, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]