Return a frame that completely erases the current frame, and then
        backs up.

        Assumes that the current frame is of constant width.

def get_erase_frame(self):
        """Return a frame that completely erases the current frame, and then
        backs up.

        Assumes that the current frame is of constant width."""
        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