I remember Prince gave me a cassette of Purple Rain. It was like 20 minutes long and he asked me to write something on it. I tried for a month and then he came to L.A. I went to see him and said, "I can't do it. It's too perfect. It's like 'Stairway to Heaven.'" He said OK and then I go, "I can keep the cassette, right?" He said, "Of course and thank you for trying."