anchor.diff:                  | Right (streamAddressLeft, env) ->
                       match evalStreamToStream name streamRight optOriginRight env with
                       | Right (streamRight, env) ->
  -                        let computedStream =
  -                            streamRight |>
  -                            Stream.product streamAddressLeft |>
  -                            Stream.map (fun event _ -> tryImportEventData event optOrigin :> obj)
  +                        let computedStream = Stream.product streamAddressLeft streamRight
                           (Stream (ComputedStream computedStream, optOrigin), env)
                       | Left violation -> (violation, env)
                   | Left violation -> (violation, env)
  
positive.code:             | _ ->
                  match evalStreamToAddress name stream optOrigin env with
                  | Right (streamAddress, env) ->
                      let stream =
                          Env.getContext env |>
                          Stream.stream streamAddress |>
                          Stream.map (fun event _ -> tryImportEventData event optOrigin :> obj)
                      Right (stream, env)
                  | Left violation -> Left violation
  
          and evalVariable name stream optOrigin env =
              match evalStreamToStream name stream optOrigin env with
              | Right (stream', env) -> (Unit optOrigin, addStream name stream' env)
              | Left violation -> (violation, env)
  
          and evalFn _ _ env =
  
negative.code:             | (Some originLeft, Some originRight) -> Some { Start = originLeft.Start; Stop = originRight.Stop }
              | (_, _) -> None
  
          let addStream name stream optOrigin env =
              let context = Env.getContext env
              let streamAddress = Address.makeFromNames [!!"Stream"; !!name] ->>- context.ParticipantAddress
              let stream = stream |> Stream.map (fun event _ -> tryImportEventData event optOrigin :> obj) |> Stream.lifetime
              let (unsubscribe, env) =
                  let world = Env.getWorld env
                  let world = match Env.tryGetStream streamAddress env with Some (_, unsubscribe) -> unsubscribe world | None -> world
  