anchor.diff:          [<CompiledName("Map")>]
           let map (f: char -> char) (str:string) =
               let str = emptyIfNull str
  -            let res = StringBuilder(str.Length)
  +            let res = StringBuilder str.Length
               str |> iter (fun c -> res.Append(f c) |> ignore)
               res.ToString()
   
           [<CompiledName("MapIndexed")>]
           let mapi (f: int -> char -> char) (str:string) =
               let str = emptyIfNull str
  -            let res = StringBuilder(str.Length)
  +            let res = StringBuilder str.Length
               let f = OptimizedClosures.FSharpFunc<_,_,_>.Adapt(f)
               str |> iteri (fun i c -> res.Append(f.Invoke(i, c)) |> ignore)
               res.ToString()
  
positive.code:     open System.Text
      open Microsoft.FSharp.Core.LanguagePrimitives.IntrinsicOperators
      open Microsoft.FSharp.Core.Operators
      open Microsoft.FSharp.Core.Operators.Checked
      open Microsoft.FSharp.Collections
  
  
negative.code:         [<CompiledName("Filter")>]
          let filter (f: char -> bool) (str:string) =
              let str = emptyIfNull str
              let res = StringBuilder str.Length
              str |> iter (fun c -> if f c then res.Append c |> ignore)
              res.ToString()
  
          [<CompiledName("Collect")>]
          let collect (f: char -> string) (str:string) =
              let str = emptyIfNull str
              let res = StringBuilder str.Length
              str |> iter (fun c -> res.Append(f c) |> ignore)
              res.ToString()
  
          [<CompiledName("Initialize")>]
          let init (count:int) (initializer: int-> string) =
              if count < 0 then invalidArgFmt "count" "{0}\ncount = {1}" [|SR.GetString SR.inputMustBeNonNegative; count|]
              let res = StringBuilder count
              for i = 0 to count - 1 do 
                 res.Append(initializer i) |> ignore
              res.ToString()
  
          [<CompiledName("Replicate")>]
          let replicate (count:int) (str:string) =
              if count < 0 then invalidArgFmt "count" "{0}\ncount = {1}" [|SR.GetString SR.inputMustBeNonNegative; count|]
              let str = emptyIfNull str
              let res = StringBuilder str.Length
              for i = 0 to count - 1 do 
                 res.Append str |> ignore
              res.ToString()
  
          [<CompiledName("ForAll")>]
  