The new single by the superstar Compton rapper arrived suddenly last week, and on it he sounds like he's been storing this venom since birth. Lamar lunges at anyone in his way on the fourth installment of a song series he started in 2010. In one set of couplets, he slams the president with rhymes about complicity and truth: "Donald Trump is a chump/ Know how we feel, punk/ Tell'em that God comin'/ And Russia need a replay button/ Y'all up to somethin'." Big Sean?) and derides disgraced former L.A. County Sheriff Lee Baca -- "tables turned, lesson learned" -- who was recently convicted of obstructing a federal investigation and then lying about his actions. Musically, "The Heart, Part 4" features contributions from producers the Alchemist, Axl Folie, Syk Sense and DJ Dahi, who collaborate on a track that rolls through a few different movements and tempos.