anchor.diff:  a document (the document in question is usually derived by the context
   the script is used). Document fields are very fast to access since they
   end up being loaded into memory (all the relevant field values/tokens
  -are loaded to memory). Note, however, that the `doc[...]` notation only 
  -allows for simple valued fields (can’t return a json object from it) 
  +are loaded to memory). Note, however, that the `doc[...]` notation only
  +allows for simple valued fields (can’t return a json object from it)
   and makes sense only on non-analyzed or single term based fields.
   
   The following data can be extracted from a field:
  
positive.code: (previously http://mvel.codehaus.org/[mvel] in 1.3.x and earlier) as the
  scripting language with some extensions. Groovy is used since it is extremely
  fast and very simple to use.
  
  Additional `lang` plugins are provided to allow to execute scripts in
  different languages. Currently supported plugins are `lang-javascript`
  
negative.code: 
  `script.groovy.sandbox.enabled`::
  
      Flag to disable the sandbox (defaults to `false` added[v1.4.3] meaning the sandbox is
      disabled).
  
  When specifying whitelist or blacklist settings for the groovy sandbox, all
  options replace the current whitelist, they are not additive.
  
  [float]
  === Automatic Script Reloading
  
  