Question: what does the mf in mf doom stand for
[{'answer': 'Metal Fingers', 'provenance': [{'wikipedia_id': '923002', 'title': 'MF Doom', 'start_paragraph_id': 12, 'start_character': 130, 'end_paragraph_id': 12, 'end_character': 143, 'bleu_score': 1.0, 'section': 'Section::::Music career.:1997–2001: "Operation Doomsday" and production work.\n'}]}, {'provenance': [{'wikipedia_id': '923002', 'title': 'MF Doom', 'start_paragraph_id': 12, 'start_character': 0, 'end_paragraph_id': 12, 'end_character': 387, 'bleu_score': 0.9663744727315161, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 6772908989055115773}, 'section': 'Section::::Music career.:1997–2001: "Operation Doomsday" and production work.\n'}]}]