Question: when did geometry dash sub zero come out
[{'answer': 'December 21 , 2017', 'provenance': [{'wikipedia_id': '43230931', 'title': 'Geometry Dash', 'start_paragraph_id': 20, 'start_character': 118, 'end_paragraph_id': 20, 'end_character': 136, 'bleu_score': 1.0, 'section': 'Section::::Spin-offs.:Geometry Dash SubZero.\n'}]}, {'provenance': [{'wikipedia_id': '43230931', 'title': 'Geometry Dash', 'start_paragraph_id': 20, 'start_character': 14, 'end_paragraph_id': 20, 'end_character': 338, 'bleu_score': 0.7002412089276221, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 4330488740095588568}, 'section': 'Section::::Spin-offs.:Geometry Dash SubZero.\n'}]}]