Question: when did the supreme court rule that bus segregation was unconstitutional
[{'answer': 'December 1956', 'provenance': [{'wikipedia_id': '151226', 'title': 'Montgomery bus boycott', 'start_paragraph_id': 11, 'start_character': 576, 'end_paragraph_id': 11, 'end_character': 589, 'bleu_score': 1.0, 'section': 'Section::::Background.:Arrest of Claudette Colvin.\n'}]}, {'provenance': [{'wikipedia_id': '151226', 'title': 'Montgomery bus boycott', 'start_paragraph_id': 11, 'start_character': 0, 'end_paragraph_id': 11, 'end_character': 589, 'bleu_score': 0.9486604584788991, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 8942708322091950565}, 'section': 'Section::::Background.:Arrest of Claudette Colvin.\n'}]}]