Today is the 50th anniversary of John Lennon’s “Instant Karma.” It was “ritten, recorded, and remixed” on January 27, 1970. It was also the beginning of the end for the Beatles. Paul McCartney was recording his first solo album, “McCartney” at the same time. It was released in April. “Let it Be” was released on May 8, 1970. And that was it. A 50th anniversary edition of “Let it Be” and the reconstituted movie, which no one has seen in five decades, are coming in May, presumably, as well as Peter Jackson’s documentary about the making of “Let it Be.” But first, Happy Anniverary, John.