CompositeObserver.remove() returning Observer?

[Robert-M-Muench]

When I have:

CompositeObserver!E  myCO;

How am I supposed to remove an observer from it?

myCO = myCO.remove(observer);

doesn't work because of an implicit conversion error. Why isn't .remove() returning a CompositeObserver!E? If there is only one observer left, it could still be a CompositeObserver!E with just one element.

[lempiji]

There is a code flow that "remove one and return the rest when there are two remaining."
I think it is relatively advantageous in terms of performance because it reduces one layer of wrapping in the class. (Maybe I'm worrying too much.)

I think CompositeObserver should be Immutable in principle, so I'll add a function that returns CompositeObserver.

[lempiji]

Please reopen if you have any concerns.

[Robert-M-Muench]

Looks good.