A core lesson from a man many consider Donald Trump’s mentor should warn the former president that his demise is coming, an expert on the man said Tuesday. Award-winning investigative reporter Andrea Bernstein quoted excerpts from her limited series about Trump’s relationship with controversial lawyer Roy Cohn, who worked with and mentored Trump during his early career. The full episodes of Bernstein’s series The Law According to Trump are on Slate’s podcast Amicus. Want more breaking political news? Click for the latest headlines at Raw Story. In it, she points out Cohn’s central philosophy. …