anchor.diff:    [<DefaultValue>] val mutable Crawler : System.Func<GetCache, Object, Environment, Box>
     [<DefaultValue>] val mutable ThrowOnMissing : bool
   
  -  static let lambdaCache = 
  -    new SafeDict<int list, System.Func<GetCache, Object, Environment, Box>>()
  -
     do x.Name <- name
     do x.ClassId <- -1
     do x.Index <- -1
  
positive.code:     let env = new Environment(sa, eg)
      //Maps
      env.AstMap <- new Dict<int, Ast.Types.Scope * Ast.Node>()
  
      //Base classes
      env.ObjectClass   <- new Class(env.NextClassId, new Dict<string, int>())
  
negative.code:               )
              )
  
            //Compile and to add it to cache
            env.GetCrawlers.[cacheKey] <- lambda.Compile()
            env.GetCrawlers.[cacheKey]
  
        //Setup cache to be ready for next hit
        x.Index   <- index //Save index so we know which offset to look at
  