Return wheter the given action is restricted for the given reftrack

        available actions are:

           ``reference``, ``load``, ``unload``, ``replace``, ``import_reference``, ``import_taskfile``, ``delete``

        If action is not available, True is returned.

        :param reftrack: the reftrack to query
        :type reftrack: :class:`Reftrack`
        :param action: the action to check.
        :type action: str
        :returns: True, if the action is restricted
        :rtype: :class:`bool`
        :raises: None

def fetch_action_restriction(self, reftrack, action):
        """Return wheter the given action is restricted for the given reftrack

        available actions are:

           ``reference``, ``load``, ``unload``, ``replace``, ``import_reference``, ``import_taskfile``, ``delete``

        If action is not available, True is returned.

        :param reftrack: the reftrack to query
        :type reftrack: :class:`Reftrack`
        :param action: the action to check.
        :type action: str
        :returns: True, if the action is restricted
        :rtype: :class:`bool`
        :raises: None
        """
        inter = self.get_typ_interface(reftrack.get_typ())
        d = {'reference': inter.is_reference_restricted, 'load': inter.is_load_restricted,
             'unload': inter.is_unload_restricted, 'replace': inter.is_replace_restricted,
             'import_reference': inter.is_import_ref_restricted, 'import_taskfile': inter.is_import_f_restricted,
             'delete': inter.is_delete_restricted,}
        f = d.get(action, None)
        if not f:
            return True
        else:
            return f(reftrack)