interface IFoo

	def isSomething(x as IFoo) as bool


class Foo implements IFoo

	def isSomething(x as IFoo) as bool
		return false

	get bar as Bar?
		return nil


class Bar implements IFoo

	def isSomething(x as IFoo) as bool
		r = false
		if x inherits Foo
			# recursive call + if-inherits-on-a-param
			# used to give false compilation error
			r = .isSomething(x.bar to !)
		return r


class Program

	def main
		pass