Prince has “enough unreleased music to put out an album every year for the next 100 years,” the documentary filmmaker who made “Hunting for Prince’s Vault” told Rolling Stone earlier this year. But this 40-song compilation from the late pop superstar’s classic Warner Bros. years contains exactly one unreleased song: “Moonbeam Levels,” a 1982 outtake from the “1999” sessions. It’s a bit dark but soothingly familiar, opening with a few kick-drum heartbeats and steam-engine noises, then shifting into “Little Red Corvette”-style vocals; by the end, Prince is moaning, “You don’t want to die.”

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Otherwise, “Prince 4Ever” mostly reshuffles 1993’s definitive “The Hits/The B-Sides” — yes, smash ’80s and ’90s hits like “When Doves Cry,” “Raspberry Beret,” “Purple Rain” and “Sexy M.F.” are here, as well as slightly deeper album tracks like “Batdance” and “Paisley Park,” from 1985’s “Around the World in a Day.” There’s nothing from Prince’s prolific post-Warner phase, beyond the early ’90s, so don’t expect a long-overdue playlist made from great but overlong albums like “Emancipation.”

As advisers and heirs sort out Prince’s estate, more unheard gems will dribble out soon, beginning with an expanded “Purple Rain” album early next year. Would Prince have authorized any of this? Probably not. But his vault is just 2 fantastic — and lucrative — 2 keep secret.