anchor.diff:  
   Functions can be declared at the beginning of the script, for example:
   
  -[source,js]
  +[source,painless]
   ---------------------------------------------------------
   boolean isNegative(def x) { x < 0 }
   ...
  
positive.code: 
  String constants can be declared with single quotes, to avoid escaping horrors with JSON:
  
  [source,js]
  ---------------------------------------------------------
  def mystring = 'foo';
  ---------------------------------------------------------
  
negative.code: 
  Map keys can also be accessed via subscript (for keys containing special characters):
  
  [source,painless]
  ---------------------------------------------------------
  return map['something-absurd!']
  ---------------------------------------------------------
  