anchor.diff:      let printEdge { Pre = s; Post = t; Cmd = vf } =
           hsep [ s |> sprintf "V%A" |> String
                  String "->"
  -               t |> sprintf "V%A" |> String
  -               String ";"]
  +               t |> sprintf "V%A" |> String ]
  +        |> withSemi
   
       /// <summary>
       ///     Prints a <c>Subgraph</c>.
  
positive.code:         hsep [ sprintf "v%A" id |> String
                 squared (hsep [ String "label"
                                 String "="
                                 view |> printGView |> ssurround "\"" "\"" ])
                 String ";" ]
  
      /// <summary>
      ///     Prints an edge.
  
negative.code:         List.append
              (nodes |> Map.toList |> List.map (uncurry printNode))
              (edges |> List.map printEdge)
          |> ivsep |> braced
  
      /// <summary>
      ///     Prints a <c>Graph</c>.
  