anchor.diff:  Iterator protocol. A new core predicate, `cljs.core/js-iterable?`
   is introduced with this feature.
   
  -For example, `(js-iterable? (js/Set.))` is `true` and 
  +For example, `(js-iterable? (js/Set.))` is `true` and
   
   [source,clojure]
   ----
  -(-> (doto (js/Set.) (.add 1) (.add 2)) 
  +(-> (doto (js/Set.) (.add 1) (.add 2))
     seq)
   ----
   
  
positive.code: 
  ### Symbol Support
  
  A new core predicate `cljs.core/js-symbol?` has been added 
  and printing has been revised to allow printing of symbols:
  
  ----
  cljs.user=> (js/Symbol "abc")
  #object[Symbol(abc)]
  ----
  
  ## More Flexable Build Support
  
  * `:bundle-cmd`
  * `:target-fn`
  * A new `--install-deps` CLI option
  * several new helper methods and facilities have
  been added to the compiler API.
  
  ## Warning Improvements
  
  
negative.code: 
  `clj-nil` is no longer considered a numeric type, so, for example `(+ nil 1)` will warn
  
  Incorrect function with fixed arity of more params than variatic now causes a
  warning. For example:
  
  ----
  cljs.user=> (defn foo ([x] 1) ([& xs] 2))
  