Question: what is the top part of a birds stomach called
[{'answer': 'proventriculus', 'provenance': [{'wikipedia_id': '5579717', 'title': 'Bird anatomy', 'start_paragraph_id': 73, 'start_character': 49, 'end_paragraph_id': 73, 'end_character': 63, 'bleu_score': 1.0, 'section': 'Section::::Digestive system.:Proventriculus.\n'}]}, {'provenance': [{'wikipedia_id': '5579717', 'title': 'Bird anatomy', 'start_paragraph_id': 73, 'start_character': 0, 'end_paragraph_id': 73, 'end_character': 679, 'bleu_score': 0.9808590314834971, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 688057330261733863}, 'section': 'Section::::Digestive system.:Proventriculus.\n'}]}]