anchor.diff:  open System.Reflection.Emit
   open Microsoft.FSharp.Reflection
   open Microsoft.FSharp.Linq.QuotationEvaluation // F# PowerPack dependency
  +
  +/// Recorder interface for verification
  +type IRecorder =
  +    abstract Invocations : System.Collections.Generic.List<obj[]>
   
   module internal CodeEmit =
       /// Boxed value
  
positive.code:         let returnValuesField = typeBuilder.DefineField("_returnValues", typeof<obj[]>, fields)
          /// Field for method arguments 
          let argsField = typeBuilder.DefineField("_args", typeof<obj[][]>, fields)
          // Generate default constructor
          generateConstructor typeBuilder [||] (fun _ -> ())
          // Set fields from constructor arguments
          let setFields (il:ILGenerator) =
              il.Emit(OpCodes.Ldarg_0)
  
negative.code:                         let x = il.DeclareLocal(abstractMethod.ReturnType)
                          il.Emit(OpCodes.Ldloca_S, x.LocalIndex)
                          il.Emit(OpCodes.Initobj, abstractMethod.ReturnType)
                          il.Emit(OpCodes.Ldloc, x.LocalIndex)
                          il.Emit(OpCodes.Ret)
              if abstractType.IsInterface then
                  typeBuilder.DefineMethodOverride(methodBuilder, abstractMethod)
  