# single optional param
class OptParam
	
	def main is shared
		x = OptParam()
		x.call = [0]
		x.foo('default')
		assert x.call == nil
		x.foo('provided',[1,4,9])
		assert x.call == [1,4,9]

	var call as List<of int>? =[0]	
	def foo(s as String, l as List<of int>? = nil) 
		#print s,i
		.call = l