Question: when did the nba add the shot clock
[{'answer': '1954', 'provenance': [{'wikipedia_id': '1002256', 'title': 'Shot clock', 'start_paragraph_id': 11, 'start_character': 40, 'end_paragraph_id': 11, 'end_character': 44, 'bleu_score': 1.0, 'section': 'Section::::History.\n'}]}, {'provenance': [{'wikipedia_id': '1002256', 'title': 'Shot clock', 'start_paragraph_id': 15, 'start_character': 0, 'end_paragraph_id': 15, 'end_character': 946, 'bleu_score': 0.8492190989675401, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 13369016020186655802}, 'section': 'Section::::History.:Creation.\n'}]}]