anchor.diff:      | MethodCall(_, Single f) ->
         let pipeLeft = pipeLeft.MakeGenericMethod([| typeof<unit>; retType |])
         Expr.TupleGet(Expr.Call(pipeLeft, [ f; <@@ () @@> ]), 0)
  -    | exprs -> failwith "oops!: %A" exprs
  +    | exprs -> failwithf "oops!: %A" exprs
   
       ProvidedMethod("Run", [parameter], info.ReturnType, IsStaticMethod = false, InvokeCode = inner)
  
positive.code:           Expr.NewTuple([ Expr.Var(v); <@@ Break @@> ]),
            cont)
        Expr.Let(v, Expr.TupleGet(x, 0), Expr.Let(c, Expr.TupleGet(x, 1), flow))
      | exprs -> failwith "oops!: %A" exprs
  
      ProvidedMethod("Combine", parameters, retType, IsStaticMethod = false, InvokeCode = inner)
  
  
negative.code:       let pt =
          match pt with
          | Some p -> p
          | 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 |])
  