def transitions(self, issue, id=None, expand=None):
        """Get a list of the transitions available on the specified issue to the current user.

        :param issue: ID or key of the issue to get the transitions from
        :param id: if present, get only the transition matching this ID
        :param expand: extra information to fetch inside each transition
        """
        params = {}
        if id is not None:
            params['transitionId'] = id
        if expand is not None:
            params['expand'] = expand
        return self._get_json('issue/' + str(issue) + '/transitions', params=params)['transitions']