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[<address@concealed>]

I'm looking for a way to do something like the following in a scenari:

$listname = [listname] . '-append'
is_subscriber($listname, [sender])...

Is there anyway to do this, either by using the right syntax in the scenari or
by creating a custom perl condition?  If the latter, can someone point me to
code that defines is_subscriber and the like are defined?  I haven't been able
to find them.

Also, I am aware that I could do this with a custom attribute, by I would
prefer not to.

Best,
Robert