Erases the screen from the current line down to the bottom of the
        screen.

def erase_down (self): # <ESC>[0J -or- <ESC>[J
        '''Erases the screen from the current line down to the bottom of the
        screen.'''

        self.erase_end_of_line ()
        self.fill_region (self.cur_r + 1, 1, self.rows, self.cols)