With a global box office of $858 million, an Oscar for Best Animated Feature, and the generally held opinion that it is one of the best (many would say it's the best) Pixar films of all time, Inside Out remains a sparkling achievement in Pixar's crowded back catalogue. A sequel to the 2015 masterpiece has felt inevitable for close to a decade now. Following up such a critical and commercial success is a staggering task. But this is the same studio that somehow delivered four Toy Story films...