Kate Anderson Brower's new book is "Team of Five: The President's Club in the Age of Trump." She explores what it means to be an ex-U.S. President and how different ex-presidents have tried to find meaning and purpose after relinquishing the presidency. Her book also examines the close friendships that have sprung up between certain ex-presidents, often surmounting differences of philosophy, personality or political affiliation. She also talks about President Trump's antagonistic rhetoric when it comes to his predecessors.