<?php // lint >= 7.4

function foo(): ?Foo
{

}

$callback = function(): ?Foo
{

};

$callback = fn ($a): ?Foo => $a;

interface Foo
{

	public function doFoo($param): ?Foo;

}

class FooBar implements Foo
{

	public function doFoo($param): ?Foo
	{

	}

}
