How do you use collections with keys?

I'm having trouble with searching for an object in a collection and inserting it if it's missing. I don't like having errors happen routinely, because that completely messes up the "break on error" functionality of the IDE.

[quote author=Adron link=board=31;threadid=4862;start=0#msg40822 date=1074893151]
How do you use collections with keys?

I'm having trouble with searching for an object in a collection and inserting it if it's missing. I don't like having errors happen routinely, because that completely messes up the "break on error" functionality of the IDE.
[/quote]

explain better what you mean.

I don't know a way of looking for an item in a collection that might not exist without possibly triggering an error. I'd like to be able to look for an item and get a status on whether it exists or not. I'd like to be able to do this without trapping an error, because trapping an error is bad.