@register(u'backward-word')
def backward_word(event):
 buff = event.current_buffer
 pos = buff.document.find_previous_word_beginning(count=event.arg)
 if pos:
  buff.cursor_position += pos

@ register ( u'backward-word' ) def backward_word ( event ) : buff = event . current_buffer pos = buff . document . find_previous_word_beginning ( count = event . arg ) if pos : buff . cursor_position += pos
move back to the start of the current or previous word .