anchor.diff:          override __.Write(s : string) = 
               buf.[ptr] <- s
               ptr <- ptr + 1
  -        override this.WriteT(s) = this.Write s
  +        override __.WriteT(s) =
  +            buf.[ptr] <- s
  +            ptr <- ptr + 1
  +
  +    type SmallStringPrintfEnv<'Result>(k) = 
  +        inherit PrintfEnv<unit, string, 'Result>(())
  +        
  +        let mutable c = null
  +
  +        override __.Finish() : 'Result = k c
  +        override __.Write(s : string) = if isNull c then c <- s else c <- c + s
  +        override __.WriteT(s) = if isNull c then c <- s else c <- c + s
   
       type StringBuilderPrintfEnv<'Result>(k, buf) = 
           inherit PrintfEnv<Text.StringBuilder, unit, 'Result>(buf)
  
positive.code:                 )
              )
  
          static member Chained4<'A, 'B, 'C, 'D, 'Tail>
              (
                  s0, conv1, s1, conv2, s2, conv3, s3, conv4,
  
negative.code:                 )
              )
  
          static member ChainedFastStart2<'A, 'B, 'Tail>
              (
                  conv1, s1, conv2,
                  next
              ) =
              (fun (env : unit -> PrintfEnv<'State, 'Residue, 'Result>) ->
                  (fun (a : 'A) (b : 'B) ->
                      let env() = 
                          let env = env()
                          Utils.Write(env, (conv1 a), s1, (conv2 b))
                          env
                      next env : 'Tail
                  )
              )
  
          static member Chained3<'A, 'B, 'C, 'Tail>
              (
                  s0, conv1, s1, conv2, s2, conv3,
  