def add_requirements(obj, *args):
    """
    Add the specified requirements to `obj`.  `obj` can be an
    :class:`lino.core.actors.Actor` or any :class:`Permittable`.
    Application code uses this indirectly through the shortcut methods
    :meth:`lino.core.actors.Actor.add_view_requirements` or a
    :meth:`Permittable.add_requirements`.
    """
    obj.required_roles |= set(args)
