code: def get_erase_frame(self):
          
          lines = self._current_frame.split('\n')
          width = len(lines[0])
          height = len(lines)
          line = ' ' * width
          if height == 1:
              frame = line + BACKSPACE * width
          else:
              frame = '\n'.join([line] * height) + BACKLINE * (height - 1)
          return frame
docs: Return a frame that completely erases the current frame, and then
          backs up.
  
          Assumes that the current frame is of constant width.