anchor.diff:                  let cattr = pcinfo.GetCustomAttributesDataImpl() 
                   defineCustomAttrs cb.SetCustomAttribute cattr
                   let ilg = cb.GetILGenerator()
  -                ilg.Emit(OpCodes.Ldarg_0)
                   let locals = Dictionary<Quotations.Var,LocalBuilder>()
                   let parameterVars = 
                       [| yield Quotations.Var("this", pcinfo.DeclaringType)
  
positive.code: type ProvidedSymbolType(kind: SymbolKind, args: Type list) =
      inherit Type()
  
      static member convType (parameters: Type list) (ty:Type) = 
          if ty.IsGenericType then 
              let args = Array.map (ProvidedSymbolType.convType parameters) (ty.GetGenericArguments())
  
negative.code:                     [| for v in parameterVars -> Quotations.Expr.Var v |]
                  match pcinfo.GetBaseConstructorCallInternal true with
                  | None ->  
                      ilg.Emit(OpCodes.Ldarg_0)
                      let cinfo = ptd.BaseType.GetConstructor(BindingFlags.Public ||| BindingFlags.NonPublic ||| BindingFlags.Instance, null, [| |], null)
                      ilg.Emit(OpCodes.Call,cinfo)
                  | Some f -> 
                      // argExprs should always include 'this'
                      let (cinfo,argExprs) = f (Array.toList parameters)
                      for argExpr in argExprs do 
                          emitExpr (ilg, locals, parameterVars) ExpectedStackState.Value argExpr
  