Question: "Purple Rain-Union" is the sixth episode of the fourth season of the animated comedy series "Bob's Burgers", it aired on Fox in the United States on which date, the title of the episode is a reference to the song, film, and album "Purple Rain" by Prince?
Sentence (from "Computer Blue"): The song was composed by Prince, with credit to his father, John L. Nelson for the guitar solo based on a piano instrumental written by Nelson and Prince.
Relevant evidence: No