import UIKit

class A { required init() {} }
class AA : A {}
class AB : A {}


func a<SomeType:A>() -> SomeType
{
    return SomeType()
}

func a<SomeType:A>() -> SomeType?
{
    return nil
}

let first  : AA? = a()
let second : AA  = a()
let third  : AB? = a()
let fourth : AB  = a()