michalmarczyk/avl.clj — pull request #1 by jafingerhut (2013-09-22 23:14:24+00:00)
Title: Throw IllegalArgumentException if last key of sorted-map has no val

Similar to error checking now done in Clojure as a result of CLJ-1052.
clojure.core/sorted-map and clojure.core/sorted-map-by also throw
exceptions in this case.