(defmacro or
  "Evaluates exprs one at a time, from left to right. If a form
  returns a logical true value, or returns that value and doesn't
  evaluate any of the other expressions, otherwise it returns the
  value of the last expression. (or) returns nil."
  ([] nil)
  ([x] x)
  ([x & next]
      `(let [or# ~x]
         (if or# or# (or ~@next)))))