code: def do_up(self, arg):
          
          if self.curindex == 0:
              self.error('Oldest frame')
              return
          try:
              count = int(arg or 1)
          except ValueError:
              self.error('Invalid frame count (%s)' % arg)
              return
          if count < 0:
              newframe = 0
          else:
              newframe = max(0, self.curindex - count)
          self._select_frame(newframe)
docs: u(p) [count]
          Move the current frame count (default one) levels up in the
          stack trace (to an older frame).