Question: when did season 2 start in fortnite battle royale
[{'answer': 'December 2017', 'provenance': [{'wikipedia_id': '56819881', 'title': 'Fortnite Battle Royale', 'start_paragraph_id': 15, 'start_character': 106, 'end_paragraph_id': 15, 'end_character': 119, 'bleu_score': 1.0, 'section': 'Section::::Gameplay.:Seasonal changes.\n'}]}]