Masters of the operetta, Gilbert and Sullivan left the musical world a legacy of marvelously playful and tuneful songs. This entertaining medley includes We Sail the Ocean Blue and (I'm Called) Little Buttercup from“HMS Pinafore,” Overture and Three Little Maids from “Mikado,” and Poor Wand'ring One, I Am the Very Model, and With Cat-Like Tread from “Pirates of Penzance.”