Clear the terminal/console screen. (Also aliased to clear.)

        Arguments:

            mode:  | 0 | 'forward'   - Clear cursor to end of screen, cursor stays.
                   | 1 | 'backward'  - Clear cursor to beginning of screen, ""
                   | 2 | 'full'      - Clear entire visible screen, cursor to 1,1.
                   | 3 | 'history'   - Clear entire visible screen and scrollback
                                       buffer (xterm).

def clear_screen(mode=2):
    ''' Clear the terminal/console screen. (Also aliased to clear.)

        Arguments:

            mode:  | 0 | 'forward'   - Clear cursor to end of screen, cursor stays.
                   | 1 | 'backward'  - Clear cursor to beginning of screen, ""
                   | 2 | 'full'      - Clear entire visible screen, cursor to 1,1.
                   | 3 | 'history'   - Clear entire visible screen and scrollback
                                       buffer (xterm).
    '''
    text = sc.erase(_mode_map.get(mode, mode))
    _write(text)
    return text