anchor.diff:      static let empty = CharSet (Diet.empty)
   
       //
  -    static let charComparer =
  -        LanguagePrimitives.FastGenericComparer<char>
  -
  -    //
       static member Empty
           with get () = empty
       
  
positive.code:     /// Applies the given function to all elements in a DIET.
      let iter (action : char -> unit) (tree : CharDiet) =
          // Preconditions
          checkNonNull "tree" tree
  
          /// Applies the action to all values within an interval.
          let intervalApplicator (lo, hi) =
  
negative.code:     /// Applies the given accumulating function to all elements in a DIET.
      let foldBack (folder : char -> 'State -> 'State) (tree : CharDiet) (state : 'State) =
          // Preconditions
          // NONE -- Skip null check because the Empty tree is represented as null.
  
          let folder = FSharpFunc<_,_,_>.Adapt folder
  
  