anchor.diff:  
               cont, contTy
   
  -        member this.PopValueUnsafe() = args.Pop()
  +        member __.PopValueUnsafe() = args.Pop()
   
           member this.PushContinuationWithType (cont : obj, contTy : Type) = 
               System.Diagnostics.Debug.Assert(this.IsEmpty, "this.IsEmpty")
  
positive.code:         let buf : string[] = Array.zeroCreate n
          let mutable ptr = 0
  
          override this.Finalize() : 'Result = k (String.Concat(buf))
          override this.Write(s : string) = 
              buf.[ptr] <- s
              ptr <- ptr + 1
          override this.WriteT(s) = this.Write s
  
      type StringBuilderPrintfEnv<'Result>(k, buf) = 
          inherit PrintfEnv<Text.StringBuilder, unit, 'Result>(buf)
          override this.Finalize() : 'Result = k ()
          override this.Write(s : string) = ignore(buf.Append(s))
          override this.WriteT(()) = ()
  
      type TextWriterPrintfEnv<'Result>(k, tw : IO.TextWriter) =
          inherit PrintfEnv<IO.TextWriter, unit, 'Result>(tw)
          override this.Finalize() : 'Result = k()
          override this.Write(s : string) = tw.Write s
          override this.WriteT(()) = ()
      
      let inline doPrintf fmt f = 
          let formatter, n = Cache<_, _, _, _>.Get fmt
  
negative.code:                 System.Diagnostics.Debug.Assert((i = n), "i = n")
                  buf.[i] <- ty
                  buf           
          go ty 0    
      
      type private PrintfBuilderStack() = 
          let args = Stack(10)
  