anchor.diff:              | (Some originLeft, Some originRight) -> Some { Start = originLeft.Start; Stop = originRight.Stop }
               | (_, _) -> None
   
  -        let addStream name stream env =
  +        let addStream name stream optOrigin env =
               let context = Env.getContext env
               let streamAddress = Address.makeFromNames [!!"Stream"; !!name] ->>- context.ParticipantAddress
  -            let stream = stream |> Stream.lifetime
  +            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
  
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:                 | Right (streamAddressLeft, env) ->
                      match evalStreamToStream name streamRight optOriginRight env with
                      | Right (streamRight, env) ->
                          let computedStream = Stream.product streamAddressLeft streamRight
                          (Stream (ComputedStream computedStream, optOrigin), env)
                      | Left violation -> (violation, env)
                  | Left violation -> (violation, env)
  