anchor.diff:  
       [<Fact>]
       let ``blah`` () : unit =
  -        let onChildAdded (evt : PersonAddedEvent) =
  +        let onChildAdded (evt : PersonAddedEvent) (state : unit) =
               match evt.ParentId with
  -            | Some parentId -> Some (parentId.ToString(), Seq.singleton ({ Id = parentId; ChildId = evt.Id } :> obj))
  -            | None -> None
  +            | Some parentId -> Seq.singleton ({ Id = parentId; ChildId = evt.Id } :> obj)
  +            | None -> Seq.empty
   
           async {
               let! connection = getConnection()
  
positive.code:                 ParentId = Some parentId
              }
  
              do! model.RunCommand addParentCmd (parentId.ToString()) |> Async.Ignore
              do! model.RunCommand addChildCmd (childId.ToString()) |> Async.Ignore
  
              do! Async.Sleep(1000)
  
              let! parentStream = connection.ReadStreamEventsBackwardAsync(parentId.ToString(), EventStore.ClientAPI.StreamPosition.End, 1, false) |> Async.AwaitTask
  
              parentStream.Events
              |> Seq.head
              |> (fun evt -> evt.Event.EventType) |> should equal "ChildAddedEvent"
          } |> Async.RunSynchronously
negative.code:     type EventProcessingConfiguration = {
          CommandHandlers : Map<string, (Type * cmdHandler)>
          StateBuilders: Set<IStateBuilder>
          EventHandlers : Map<string, (Type *  (obj -> option<(string *  IStateBuilder * (obj -> seq<obj>))>))>
      }
      with static member Empty = { CommandHandlers = Map.empty; StateBuilders = Set.empty; EventHandlers = Map.empty } 
  
  