def group_for_policy(self, policy=None):
        """
        Lookup the collective.workspace usergroup corresponding to the
        given policy

        :param policy: The value of the policy to lookup, defaults to the
                       current policy
        :type policy: str
        """
        if policy is None:
            policy = self.context.participant_policy
        return "%s:%s" % (policy.title(), self.context.UID())