code: def downvote(self):
          
          url = self._imgur._base_url + "/3/gallery/{0}/vote/down".format(self.id)
          return self._imgur._send_request(url, needs_auth=True, method='POST')
docs: Dislike this.
  
          A downvote will replace a neutral vote or an upvote. Downvoting
          something the authenticated user has already downvoted will set the
          vote to neutral.