anchor.diff:  
       //
       [<CompiledName("FoldIndexed")>]
  -    let foldi (folder : 'State -> int -> char -> 'State) state (substring : Substring) : 'State =
  +    let foldi (folder : 'State -> int -> char -> 'State) state (substring : substring) : 'State =
           // OPTIMIZATION : Immediately return if the substring is empty.
           let len = substring.Length
           if len = 0 then state
  
positive.code:     [<CompiledName("OfArray")>]
      let inline ofArray (chars : char[]) =
          System.String (chars)
  
      /// Returns the index of the first occurrence of a specified character within a string.
      [<CompiledName("TryFindIndexOf")>]
  
negative.code:             notImpl "String.Split.iter"
  
          //
          [<CompiledName("IterIndexed")>]
          let iteri (separator : char[]) (action : int -> substring -> unit) (str : string) : unit =
              // Preconditions
              checkNonNull "separator" separator
              checkNonNull "str" str
  