fun all: Set[NitniCallback]
	do
		var cached = all_cached
		if cached != null then return cached

		var set = new HashSet[NitniCallback]
		set.add_all(callbacks)
		set.add_all(supers)
		set.add_all(types)
		set.add_all(casts)
		
		self.all_cached = set
		return set
	end