code: def do_show(self, args):
          
          args = args.strip()
  
          to_show = self._interp._root
          if args != "":
              try:
                  to_show = self._interp.eval(args)
              except Exception as e:
                  print("ERROR: " + e.message)
                  return False
  
          if hasattr(to_show, "_pfp__show"):
              print(to_show._pfp__show())
          else:
              print(repr(to_show))
docs: Show the current structure of __root (no args),
          or show the result of the expression (something that can be eval'd).