Question:  Donald Corren is an American Broadway and film actor and screenwriter who created the role of Cosmé McMoon opposite Judy Kaye's Florence Foster Jenkins,  an American socialite and amateur soprano who was known and mocked for her flamboyant performance costumes and what poor ability?
Sentence (from "Florence Foster Jenkins"): "No one, before or since," he wrote, "has succeeded in liberating themselves quite so completely from the shackles of musical notation."
Relevant evidence: No