Register a vote for the current authenticated user on an issue.

        :param issue: ID or key of the issue to vote on
        :rtype: Response

def add_vote(self, issue):
        """Register a vote for the current authenticated user on an issue.

        :param issue: ID or key of the issue to vote on
        :rtype: Response
        """
        url = self._get_url('issue/' + str(issue) + '/votes')
        return self._session.post(url)