anchor.diff:  
               // book keeping
               let execOp = List.head strmToProcess       
  -            let streamCallHistory = strmIdToProcess :: streamCallHistory
               let remainingStreams = streams |> List.map (fun strm -> 
                   if strm = strmToProcess then List.tail strm
                   else strm)
  
positive.code:                         match !evtp with
                          | Some evt when
                              activeEvents |> List.exists (fun e -> e.EventObjectId = evt.EventObjectId) -> false
                              // EmitEvent may only be called again for a given event,
                              // after all necessary calls to WaitOnEvent for a previous correlation.
                          | _ -> true
                      | [] -> false
  
negative.code: //                // TODO
  //                generate streamCallHistory activeEvents remainingStreams
              | _ as eop -> 
                  let streamCallHistory = strmIdToProcess :: streamCallHistory
                  ExeOp(strmIdToProcess, eop) :: generate streamCallHistory activeEvents remainingStreams
          else
              // streams are all empty
  