class A
	pass

class B
	inherits A
	pass

class Test

	def main is shared
		t = Test()
		t.foo(5)  # .error. Argument 1 of method "foo" expects type String, but the call is supplying type int.

		b as B?
		b = B()
		t.bar(b)  # .error. Argument 1 of method "bar" expects a non-nilable type (A), but the call is supplying a nilable type (B?).

	def foo(s as String)
		pass

	def bar(a as A)
		pass