class A

	var _e as E

	cue init
		base.init
		_e = F()

	def run
		if _e inherits F
			_e = _e.backUp
			_e.foo  # access _e after it has been "backed up" to a higher type


class E

	def foo
		pass


class F inherits E
	
	get backUp as E
		return E()


class Test

	def main is shared
		A().run