anchor.diff:        let pt =
           match pt with
           | Some p -> p
  -        | None -> failwith "not found FSharpFunc<'T1, 'T2> in %s" info.Name
  +        | None -> failwithf "not found FSharpFunc<'T1, 'T2> in %s" info.Name
         let f =
           let tuple = Var("tuple", retType)
           let composeRight = composeRight.MakeGenericMethod([| pt; retType; info.ReturnType |])
  
positive.code: 
      let inner = function
      | MethodCall(_, Single f) -> f
      | exprs -> failwith "oops!: %A" exprs
  
      ProvidedMethod("Delay", [parameter], parameter.ParameterType, IsStaticMethod = false, InvokeCode = inner)
  
  
negative.code:           Expr.NewTuple([ Expr.Var(v); <@@ Break @@> ]),
            cont)
        Expr.Let(v, Expr.TupleGet(x, 0), Expr.Let(c, Expr.TupleGet(x, 1), flow))
      | exprs -> failwithf "oops!: %A" exprs
  
      ProvidedMethod("Combine", parameters, retType, IsStaticMethod = false, InvokeCode = inner)
  
  