--- CIDRs. Reduce, on the other hand, will combine any
--- redundant/adjacent CIDR blocks into one. Dupe will show you what
--- would be removed by Reduce, and Diff will show both additions and
--- deletions in a diff-like format.
-data Mode = Regex | Reduce | Dupe | Diff
+-- CIDRs.
+--
+-- Reduce, on the other hand, will combine any redundant/adjacent
+-- CIDR blocks into one.
+--
+-- Dupe will show you what would be removed by Reduce.
+--
+-- Diff will show both additions and deletions in a diff-like
+-- format.
+--
+-- List will enumerate the IP addresses contained within the input
+-- CIDRs.
+--
+-- Reverse will perform a reverse DNS (PTR) lookup on each IP
+-- address contained within the input CIDRs.
+--
+data Mode = Regex | Reduce | Dupe | Diff | List | Reverse