Of course! A quick Google search for [site:arclanguage.org testify iso] turns up a few places Arc Forumgoers have talked about this before:
http://arclanguage.org/item?id=9183 (aw)
http://arclanguage.org/item?id=13678 (me)
http://arclanguage.org/item?id=13267 (me and you)
These were just my first three search results. :)
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"A caller of either shouldn't typically care whether they create new conses or not."
Does anyone mutate association lists? It might matter there.
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