Since taking office, President Trump and his advisor, billionaire business owner Elon Musk, have worked to winnow the ranks of federal workers. At times questioning the contributions of some federal employees, they are also enticing more than two million government employees to quit, and have moved to shutter entire agencies. But how will the public lose out if government workers lose their jobs? “Sunday Morning” national correspondent Robert Costa talks with Christopher Mark, a Department of Labor engineer who has helped keep coal miners safe and alive; and with Michael Lewis, editor of the new book “Who Is Government?,” which explores a workforce of individuals dedicated to the public good.