title: How and when is ray.method(num_return_values) used?
body: <p>The ray tutorial explains, that for having a method on an object, which returns multiple object_ids one can use the @ray.method() decorator <a href="https://ray.readthedocs.io/en/latest/actors.html#actor-methods" rel="nofollow noreferrer">see here</a>. But in the example 'Learning to play Pong' the method <em>compute gradient</em> actually has two return values, which are called as object_ids later, but it is not coded as ray.method with the respective decorator<a href="https://ray.readthedocs.io/en/latest/auto_examples/plot_pong_example.html#parallelizing-gradients" rel="nofollow noreferrer">see here</a>. I would like to understand what the use of ray.method is now. </p>