def add_role(self, role, parents=[]):
        self._roles.setdefault(role, set())
        self._roles[role].update(parents)
        for p in parents:
            self._children.setdefault(p, set())
            self._children[p].add(role)

        # all roles start as deny-only (unless one of its parents isn't deny-only)
        if not parents or self._roles_are_deny_only(parents):
            self._denial_only_roles.add(role)
Add a role or append parents roles to a special role.
dataset/ETHPy150Open tonyseek/simple-rbac/rbac/acl.py/Registry.add_role