anchor.diff:  
   [source, clojure]
   ----
  -[org.clojure/clojure "1.9.0-alpha8"]
  +[org.clojure/clojure "1.9.0-alpha9"]
   ----
   
   To start working with spec, require the `clojure.spec` namespace or include in your namespace definition:
  
positive.code: ;;     :type :pass})
  ----
  
  `test` also takes a number of options that can be passed to test.check to influence the test run, as well as the option to override generators for parts of the spec, by either name or path.
  
  Imagine instead that we made an error in the ranged-rand code and swapped start and end:
  
  
negative.code: 
  [source,clojure]
  ----
  (stest/abbrev-result (first (stest/check `ranged-rand)))
  ;;=> ({:spec (fspec
  ;;            :args (and (cat :start int? :end int?) (fn* [p1__3468#] (< (:start p1__3468#) (:end p1__3468#))))
  ;;            :ret int?
  