# inheritance of generic of nilable type
class A inherits Dictionary<of int, Object?>

	pass
		

class X

	# argument of generic of nilable type
	def foo(expectedCount as int, objects as IEnumerable<of Object?>)
		results = []
		for object in objects
			if object, results.add(object)
		assert results.count == expectedCount

	def main
		.foo(2, [nil, 5, nil, 'aoeu'])

		a = A()
		a[3] = 'aoeu'
		a[4] = nil
		assert a.count == 2
		assert a[3] == 'aoeu'
		assert a[4] == nil