Question: when did under god become part of the pledge of allegiance
[{'answer': 'Flag Day 1954'}, {'provenance': [{'wikipedia_id': '59581', 'title': 'Pledge of Allegiance', 'start_paragraph_id': 1, 'start_character': 4, 'end_paragraph_id': 1, 'end_character': 533, 'bleu_score': 0.603657145882859, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 6375441818855656656}, 'section': 'Section::::Abstract.'}]}]