Question: who plays ds arnott in line of duty
[{'answer': 'Martin Compston', 'provenance': [{'wikipedia_id': '1909909', 'title': 'Martin Compston', 'start_paragraph_id': 0, 'start_character': 0, 'end_paragraph_id': 0, 'end_character': 15, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '1909909', 'title': 'Martin Compston', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 353, 'bleu_score': 0.7734458776501301, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 1327318108667404494}, 'section': 'Section::::Abstract.'}]}]