Question: who plays dr. walcott in the big bang theory
[{'answer': 'Peter MacNicol', 'provenance': [{'wikipedia_id': '50375161', 'title': 'The Big Bang Theory (season 11)', 'start_paragraph_id': 38, 'start_character': 12, 'end_paragraph_id': 38, 'end_character': 26, 'bleu_score': 1.0, 'section': 'Section::::Cast.:Guest cast.\n'}]}]