Question: who is opening for shawn mendes in pittsburgh
[{'answer': 'Charlie Puth', 'provenance': [{'wikipedia_id': '51613487', 'title': 'Illuminate World Tour', 'start_paragraph_id': 4, 'start_character': 22, 'end_paragraph_id': 4, 'end_character': 34, 'bleu_score': 1.0, 'section': 'Section::::Background and development.\n'}]}]