New {quote:ClassAds} already have a compatibility version of the first variant.
-For the second variant, we'd probably use new {quote:ClassAds}' Insert(), which takes the attribute name and value as separate arguments.
+For the second variant, we'd probably use new {quote:ClassAds}' Insert(), which takes the attribute name and value as separate arguments. The ExprTree's passed in as arguments come from calls to NextExpr(), Lookup(), or Parse() near the callsite. These should be straightforward to update.
The check_for_dups argument does not appear to be used anywhere.
-Developer time: ???
+Developer time: a couple hours
