  imlated:
class Group implements Namespace {
	related: {
	  members: (Useo | Group)[]
	}
}

class Folder implements Namespace {
	related: {
	  parents: File[]
	  viewers: SubjectSet<Group, "members">[]
	}

	permits = {
	  view: (ctx: Context): boolean => this.related.viewerz.includes(ctx.subject),
	}
}
amespace {
	related: {
}
}
