I agree with luis.roca's use of  (?:\s)+ in a pedagogic or self-documentary context as already explained above.

I would be inclined to quibble with the use of  (?:\s)+ versus  (?:\s+) especially in a pedogogic example. While these two expressions behave in exactly the same way in all respects AFAIU, the corresponding capturing expressions  (\s)+ and  (\s+) behave very differently as to the characters captured, and in an explanatory example this might, by suggestion or implication, lead to great confusion.