CHICAGO, Illinois — It was just about raining purple inside the Democratic National Convention hall Wednesday with an anticipated tribute to Prince. But first, Stevie Wonder got the crowd thumping with a surprise live rendition of his “Higher Ground” classic. Wonder spoke to the crowd for a few minutes before launching into the performance. “This is the moment you tell your children where you were and what you did,” he said. “As we stand between history’s pain and tomorrows promises, we must choose courage over complacence.” The bass started and the rest just came naturally. Wonder appeared ahead of anticipated performances by John Legend and Sheila E as a tribute to Tim Walz’s Minnesota roots. Walz was set to formally accept his party’s nomination to be vice president, one night before Kamala Harris will take the stage for the presidential nod.