anchor.diff:  module Helpers =
       let inline ni () = raise (new System.NotImplementedException ())
   
  +[<NoEquality>]
   type internal MetadataReference =
   | FileMetadataReference of string
   | ImageMetadataReference of string * byte array
  
positive.code:         with get () =
              match r with
              | FileMetadataReference f -> f
              | ImageMetadataReference (p, a) -> p
              | ProjectMetadataReference (p, a) -> p
  
  [<CompilationRepresentationAttribute(CompilationRepresentationFlags.ModuleSuffix)>]
  module internal MetadataReference =
  
negative.code: 
              // Implement the service related to temporary paths and file time stamps
              member fs.GetTempPathShim () = 
                  tprintfn "GetTempPathShim: ()" ()
                  defaultFileSystem.GetTempPathShim ()
  
              member fs.GetLastWriteTimeShim name = 
  