Nas's new album Life Is Good is imminent, and all the tracks we've heard -- "Nasty," "The Don," "Daughters," "Accident Murderers" -- find the man doing something to recapture the inventive, technically rigorous ferocity he had when he was younger. "Loco-Motive," his newest track, works along the same lines. It's a prime slice of honking NY rap, and it features ...