Question: what is the function of von willebrand factor
[{'answer': 'binding to other proteins', 'provenance': [{'wikipedia_id': '623174', 'title': 'Von Willebrand factor', 'start_paragraph_id': 20, 'start_character': 44, 'end_paragraph_id': 20, 'end_character': 69, 'bleu_score': 1.0, 'section': 'Section::::Biochemistry.:Function.\n'}]}, {'answer': 'important in platelet adhesion', 'provenance': [{'wikipedia_id': '623174', 'title': 'Von Willebrand factor', 'start_paragraph_id': 20, 'start_character': 108, 'end_paragraph_id': 20, 'end_character': 138, 'bleu_score': 1.0, 'section': 'Section::::Biochemistry.:Function.\n'}]}, {'provenance': [{'wikipedia_id': '623174', 'title': 'Von Willebrand factor', 'start_paragraph_id': 20, 'start_character': 0, 'end_paragraph_id': 20, 'end_character': 211, 'bleu_score': 0.9451524926983921, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 14024818936703013866}, 'section': 'Section::::Biochemistry.:Function.\n'}]}]