Question: who sings at the end of bullet by hollywood undead
[{'answer': 'Petra Christensen', 'provenance': [{'wikipedia_id': '32793811', 'title': 'Bullet (Hollywood Undead song)', 'start_paragraph_id': 7, 'start_character': 1688, 'end_paragraph_id': 7, 'end_character': 1705, 'bleu_score': 1.0, 'section': 'Section::::Composition and lyrics.\n'}]}, {'provenance': [{'wikipedia_id': '32793811', 'title': 'Bullet (Hollywood Undead song)', 'start_paragraph_id': 7, 'start_character': 0, 'end_paragraph_id': 7, 'end_character': 1830, 'bleu_score': 0.9698776336490801, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 2376660608012830492}, 'section': 'Section::::Composition and lyrics.\n'}]}]