anchor.diff:      let env = new Environment(sa, eg)
       //Maps
       env.AstMap <- new Dict<int, Ast.Types.Scope * Ast.Node>()
  +    env.GetCrawlers <- new Dict<int list, System.Func<GetCache, Object, Environment, Box>>()
   
       //Base classes
       env.ObjectClass   <- new Class(env.NextClassId, new Dict<string, int>())
  
positive.code:   [<DefaultValue>] val mutable FunctionClass : Class
    [<DefaultValue>] val mutable Object_prototype : Object
    [<DefaultValue>] val mutable Function_prototype : Object
    [<DefaultValue>] val mutable AstMap : Dict<int, Ast.Types.Scope * Ast.Node>
  
    member x.GetDelegate (func:Function) delegateType types =
      let cell = new DelegateCell(func.AstId, func.ClosureId, delegateType)
  
negative.code:   [<DefaultValue>] val mutable Crawler : System.Func<GetCache, Object, Environment, Box>
    [<DefaultValue>] val mutable ThrowOnMissing : bool
  
    do x.Name <- name
    do x.ClassId <- -1
    do x.Index <- -1
  