anchor.diff:  
   // Introduction
   
  -Closure compiler can process AMD, CommonJS and ES6 modules giving a good support for
  +Closure compiler can process AMD, CommonJS and ES6 modules giving good support for
   link:/news/2017-07-12-clojurescript-is-not-an-island-integrating-node-modules[leveraging Node ecosystem].
   // not sure this is worth mention, as I can't find good source for what is really supported
   // footnote:[Closure also supports TypeScript, but this has not been tested with Cljs yet.]
  
positive.code: 
  The option is enabled by providing `:preprocess` option to a link:/reference/compiler-options#foreign-libs[foreign-lib map].
  The value is a keyword and is used as dispatch value for `cljs.closure/js-transforms`
  multimethod.  Implementing a transformation requires writing a new method for that multimethod.
  The namespace that proivdes this method has to be loaded before ClojureScript
  compiler is run. One problem has been that there has not been support in popular build tools
  for this feature.
  
negative.code: === Preprocess symbol
  
  If the `:preprocess` option value is a symbol ClojureScript compiler will
  resolve the symbol to a Clojure function, and call the function to process the JS code.
  Using symbols over keywords has the benefit of there being
  relation between the symbol and the namespace where function is defined.
  This allows ClojureScript compiler to automatically load
  