anchor.diff:      
       ///Adds a labeled, edge to the graph.
       member this.AddEdge((s, t, w): LEdge<'Vertex,'Edge>) =
  -        if s = t then 
  -            let edgeArraySource = 
  -                try
  -                    vertexOutEdges.Item s
  -                with 
  -                |_ -> failwithf "The source vertex %O of the edge does not exist in this graph." s
  -
  -            vertexOutEdges.Item s <- (Array.concat [[|(s,t,w);(s,t,w)|];edgeArraySource])
  -
  -        else
  -            let edgeArraySource = 
  -                try
  -                    vertexOutEdges.Item s
  -                with 
  -                |_ -> failwithf "The source vertex %O of the edge does not exist in this graph." s
  -
  -            let edgeArrayTarget = 
  -                try
  -                    vertexOutEdges.Item t
  -                with
  -                |_ -> failwithf "The target vertex %O of the edge does not exist in this graph." t
  -
  -        
  -            vertexOutEdges.Item s <- (Array.concat [[|(s,t,w)|];edgeArraySource])
  -            vertexOutEdges.Item t <- (Array.concat [[|(s,t,w)|];edgeArrayTarget])
  +
  +        let edgeArraySource = 
  +            try
  +                vertexOutEdges.Item s
  +            with 
  +            |_ -> failwithf "The source vertex %O of the edge does not exist in this graph." s
  +
  +        let edgeArrayTarget = 
  +            try
  +                vertexOutEdges.Item t
  +            with
  +            |_ -> failwithf "The target vertex %O of the edge does not exist in this graph." t
  +
  +        
  +        vertexOutEdges.Item s <- (Array.concat [[|(s,t,w)|];edgeArraySource])
  +        vertexOutEdges.Item t <- (Array.concat [[|(s,t,w)|];edgeArrayTarget])
   
           this
       
  
positive.code:     
      ///Removes an edge from the graph.
      member this.RemoveEdge((s, t, w): LEdge<'Vertex,'Edge>) =
          let edgeArraySource = 
              try 
                  vertexOutEdges.Item s
                  |> Array.filter (fun x -> x <> (s, t, w) )
              with
              |_ -> failwithf "The source vertex %O of the edge does not exist in this graph." s
  
          let edgeArrayTarget = 
              try
                  vertexOutEdges.Item t
                  |> Array.filter (fun x -> x <> (s, t, w) )
              with
              |_ -> failwithf "The target vertex %O of the edge does not exist in this graph." t        
          
          vertexOutEdges.Item s <- (edgeArraySource)
          vertexOutEdges.Item t <- (edgeArrayTarget)
          this
  
      ///Removes an array of edges from the graph.
  
negative.code:                 //Array.filter (fun (s, t, w) -> s=vertex || t=vertex) edgeArray         
                  edgeArray
                  |> Array.filter (fun (s, t, w) -> s=vertex || t=vertex) 
                  //|> Array.map (fun (s,t,w) -> 
                  //    if s=t then [|(s,t,w);(s,t,w)|]
                  //    else [|(s,t,w)|])
                  //|> Array.concat
  
              labelDict.Add (vertex,label)                                  
              vertexEdges.Add (vertex,edges)
  