Send message to a Set<Room> #5418

Is your feature request related to a problem? Please describe.
I would like to send a message to a Set of Rooms.

Describe the solution you'd like
Since 085d1de, socket.io accepts an array.
To go further, it could accept Sets, or even iterables.

Describe alternatives you've considered
In the meantime, I'm simply using Array.from(...).

Additional context
This feature is obviously not mandatory, but I think a number of developers would benefit from it.