‘Side by Side’ is more than just a musical review BOULDER, Colo. — Imagine hanging out with legendary composer and lyricist Stephen Sondheim and a few of his closest friends—Bernadette Peters, Leonard Bernstein, Mandy Patinkin and others—as they chat and swing into some of his greatest works. That’s what you’ll experience onstage when CU Opera performs “Side by Side by Sondheim” April 24-27.