cond

(cond test expr... test expr...)

Takes the test/expression pairs in order and, at the first truthy test, evaluates that expression and answers it; with no pair taken the answer is nil. :else is true, so it works as the catch-all. An ODD trailing arm -- a lone test with no expression -- is taken as the default, answering the test's value, where Clojure rejects the malformed parity.

Deviation: the odd trailing arm is accepted as the default; Clojure requires an even form count.