anchor.diff:  open Fable.AST.Fable
   open Fable.Transforms
   open Replacements.Util
  +
  +type NumberKind with
  +    member this.Number =
  +        Number(this, NumberInfo.Empty)
   
   let (|DartInt|_|) = function
       | Int8 | UInt8 | Int16 | UInt16 | Int32 | UInt32 | Int64 | UInt64 -> Some DartInt
  
positive.code: 
  // Mirrors Fable2Dart.Util.compare
  and compare (com: ICompiler) ctx r (left: Expr) (right: Expr) =
      let returnType = Number(Int32, NumberInfo.Empty)
      match left.Type with
      | Array _ -> Helper.LibCall(com, "Util", "compareList", returnType, [left; right], ?loc=r)
      | Boolean -> Helper.LibCall(com, "Util", "compareBool", returnType, [left; right], ?loc=r)
  
negative.code:         | Operators.addition, [left; right] ->
              match argTypes with
              | Char::_ ->
                  let toUInt16 e = toInt com ctx None UInt16.Number [e]
                  Operation(Binary(BinaryPlus, toUInt16 left, toUInt16 right), UInt16.Number, r) |> toChar
              | _ -> binOp BinaryPlus left right
          | Operators.subtraction, [left; right] -> binOp BinaryMinus left right
          | Operators.multiply, [left; right] -> binOp BinaryMultiply left right
  