anchor.diff:          let observation = { ObserverAddress = observation.ObserverAddress; Subscribe = subscribe }
           observation.Subscribe world |> _bc
   
  -    /// Subscribe an observation, handling each event with the given 'handleEvent' procedure.
  +    /// Subscribe to an observation, handling each event with the given 'handleEvent' procedure.
       let subscribe handleEvent observation world =
           subscribeWithUnsub handleEvent observation world |> snd
   
  
positive.code:             (subscriptionAddress, unsubscribe, world)
          { ObserverAddress = observation.ObserverAddress; Subscribe = subscribe }
  
      /// Terminate an observation when the observing simulant is removed from the world.
      let lifetime (observation : Observation<'a, 'o>) : Observation<'a, 'o> =
          until (RemovingEventAddress ->>- observation.ObserverAddress) observation
  
      /// Subscribe to an observation until the observing simulant is removed from the world,
      /// returning both an unsubscription procedure as well as the world as augmented with said
      /// subscription.
      let monitorWithUnsub eventAddress observation world =
          (observation |> lifetime |> subscribeWithUnsub eventAddress) world
  
      /// Subscribe an observation until the observing simulant is removed from the world.
      let monitor eventAddress observation world =
          monitorWithUnsub eventAddress observation world |> snd
      
  
negative.code:             (subscriptionAddress, unsubscribe, world)
          { ObserverAddress = observation.ObserverAddress; Subscribe = subscribe }
  
      /// Subscribe to an observation, handling each event with the given 'handleEvent' procedure,
      /// returning both an unsubscription procedure as well as the world as augmented with said
      /// subscription.
      let subscribeWithUnsub handleEvent observation world =
  