Question: where is american airlines hub in the us
[{'answer': 'Dallas / Fort Worth', 'provenance': [{'wikipedia_id': '2386', 'title': 'American Airlines', 'start_paragraph_id': 110, 'start_character': 209, 'end_paragraph_id': 110, 'end_character': 240, 'bleu_score': 1.0, 'section': 'Section::::Corporate affairs.:Headquarters.\n'}]}, {'answer': 'Charlotte', 'provenance': [{'wikipedia_id': '2386', 'title': 'American Airlines', 'start_paragraph_id': 13, 'start_character': 12, 'end_paragraph_id': 13, 'end_character': 21, 'bleu_score': 1.0, 'section': 'Section::::Destinations and hubs.:Hubs.\n'}]}, {'answer': "Chicago -- O'Hare"}, {'answer': 'Philadelphia', 'provenance': [{'wikipedia_id': '2386', 'title': 'American Airlines', 'start_paragraph_id': 106, 'start_character': 612, 'end_paragraph_id': 106, 'end_character': 624, 'bleu_score': 1.0, 'section': 'Section::::Reward programs.:Flagship Lounge.\n'}]}, {'answer': 'Miami', 'provenance': [{'wikipedia_id': '2386', 'title': 'American Airlines', 'start_paragraph_id': 106, 'start_character': 502, 'end_paragraph_id': 106, 'end_character': 507, 'bleu_score': 1.0, 'section': 'Section::::Reward programs.:Flagship Lounge.\n'}]}, {'answer': 'Phoenix -- Sky Harbor'}, {'answer': 'Washington , DC -- National'}, {'answer': 'Los Angeles', 'provenance': [{'wikipedia_id': '2386', 'title': 'American Airlines', 'start_paragraph_id': 75, 'start_character': 138, 'end_paragraph_id': 75, 'end_character': 149, 'bleu_score': 1.0, 'section': 'Section::::Cabins.\n'}]}, {'answer': 'New York -- JFK'}, {'answer': 'New York -- LaGuardia'}]