“Yes, encores are as predictable as a Nor’easter in January. Yes, crowd members not only can predict that there will usually be an encore, they can sometimes name at least one song that will be performed — for Prince, it’s ”Purple Rain”; for Patti LaBelle, it’s ”Over the Rainbow.” Still, encores are part of the unwritten covenant between artist and audience. It’s dessert, the last bit of sweetness to polish off a stunning meal. The main show finishes, the fans stomp and scream, fire up their lighters if they’re feeling kitschy, and when the artist feels he has been duly adored, he returns like a conquering hero.”