The chairwoman of the Nevada Democratic Party received more than a thousand angry phone calls and texts since the state’s Democratic convention over the weekend. Roberta Lange led the convention to assign delegates to Hillary Clinton and Bernie Sanders, and she’s now being inundated by furious Bernie Sanders supporters who say that some of their delegates were unfairly excluded and that the convention is an example of how the system is rigged in favor of establishment candidates. We’ve heard a lot this political season about the anger and infighting among Republicans. Is there as much vitriol on the left?