anchor.diff:  
               member __.GetLastWriteTimeShim (fileName:string) = File.GetLastWriteTime fileName
               member __.SafeExists (fileName:string) = System.IO.File.Exists fileName 
  -            member __.FileDelete (fileName:string) = System.IO.File.Delete fileName }       
  +            member __.FileDelete (fileName:string) = System.IO.File.Delete fileName
   #endif
   
       type System.Text.Encoding with 
  
positive.code:     open System.Windows
      open System
  
      let mutable FileSystem = 
          { new IFileSystem with 
              member this.ReadAllBytesShim (fileName:string) = 
                  use stream = this.FileStreamReadShim fileName
                  let len = stream.Length
  
negative.code:                 match Application.GetResourceStream(System.Uri(fileName,System.UriKind.Relative)) with 
                  | null -> IsolatedStorageFile.GetUserStoreForApplication().DeleteFile fileName
                  | _resStream -> ()
  #else
  
      type DefaultFileSystem() =
          interface IFileSystem with
              member __.AssemblyLoadFrom(fileName:string) = 
      #if FX_ATLEAST_40_COMPILER_LOCATION
                  System.Reflection.Assembly.UnsafeLoadFrom fileName
  