anchor.diff:                      yield neighbors }
       
       /// shows the adjacency matrix in the console
  -    member system.ShowAdjList () =
  +    member this.ShowAdjList () =
           Seq.iter (fun ls -> Seq.iter (fun c -> printf "%A" c) ls
                               printfn "") adjacencyList
   
       /// shows the health of each computer
  -    member system.ShowSystem () =
  +    member this.ShowSystem () =
           let fontColor (comp:Computer) =
               if comp.IsInfected () then System.Console.ForegroundColor <- System.ConsoleColor.Red
               else System.Console.ForegroundColor <- System.ConsoleColor.Gray
  
positive.code: //    member val OperatingSystem = os with get, set
      
      /// ID of computer in local network                                    ????????????????????????????????????????
      member val ID = 0 with get
      
      /// checks the health of computer
      member comp.IsInfected () = isInfected;
      
      /// simulates a viral attack on the computer
      member comp.Infect damagePoint =
          if damagePoint >= healthPoints then
              isInfected <- true
  
  
negative.code:             else "healthy"
          Seq.iter (fun x -> fontColor x
                             System.Console.WriteLine("computer number " + x.ID.ToString () + " is " + (health x))) computers
      
  
  
      /// returns a list of healthy computers
      member this.GetHealthyComputers () =
          Array.fold (fun acc (comp:Computer) -> if comp.IsInfected () then (comp.ID :: acc) else acc) [] computers
  
  //    member IsUnHealthy () =
  //        Seq
  