exit status: 1 with stderr:
<stdin>:10:5: error: overridden method 'init' has generic signature <T where T : Q> which is incompatible with base method's generic signature <T where T : P>; expected generic signature to be <T where T : P> init<T: Q>(_ x: T) { ^ <stdin>:6:5: note: overridden declaration is here init<T: P>(_ x: T) {} ^