Ted Rall's graphic novel Bernie explores the personal and political development of Bernie Sanders, a man who looks set to shake up the 2016 US presidential campaign and redefine the left wing of the Democratic Party. America's answer to Jeremy Corbyn, Sanders - a self-identified socialist - has been relentlessly marginalized and ridiculed by the national political power brokers and the media that supports them. But who is this man? And what accounts for his sudden rise in popularity?