anchor.diff:  
           // Return the index of the matching character, if any.
           if foundMatch then
  -            Some index
  +            // Subtract one from the index since it was incremented after finding
  +            // the match but before the loop terminated.
  +            Some (index - 1)
           else None
   
       /// Returns the index of the first character in the string which satisfies the given predicate.
  
positive.code:         str.ToCharArray ()
  
      /// Returns a string array that contains the substrings in a string that are delimited
      /// by elements of the given Unicode character array.
      [<CompiledName("Split")>]
      let inline split (chars : char[]) (str : string) =
          str.Split chars
  
      /// <summary>Returns a new string created by concatenating the strings in the specified string array.</summary>
      /// <remarks>
  
negative.code:             // Create a new string from the chosen characters.
              ofArray chosenChars.[..chosenCount-1]
  
      /// Removes all leading and trailing occurrences of
      /// the specified characters from a string.
      [<CompiledName("Trim")>]
      let inline trim (chars : char[]) (str : string) =
          str.Trim chars
  
      /// Removes all leading occurrences of the specified set of characters from a string.
  