class OptParam
	def main is shared
		x = OptParam()
		assert x.val ==0 and x.isOn == false
		x.isOn = true
		x.foo('this')
		assert x.val ==1 and x.isOn == false
		x.isOn = true
		x.foo('is', 10)
		assert x.val == 10 and x.isOn == false
		x.foo('sparta', 20, true)
		assert x.val == 20 and x.isOn == true

	var val = 0
	var isOn = false
	
	def foo(s as String, i as int = 1, isOn as bool = false)
		.val = i
		.isOn = isOn