Question: which leader halted the muslim invasion of western europe at the battle of tours
[{'answer': 'Charles Martel', 'provenance': [{'wikipedia_id': '46674', 'title': 'Battle of Tours', 'start_paragraph_id': 1, 'start_character': 211, 'end_paragraph_id': 1, 'end_character': 225, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '46674', 'title': 'Battle of Tours', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 660, 'bleu_score': 0.7738557947138821, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 5447499709523611743}, 'section': 'Section::::Abstract.'}]}]