anchor.diff:  
       let files_to_transorm = pages |> Array.append <| posts 
   
  -    // the actual renderer to be used.  you can use a fake_renderer to bypass
  -    // any issues with Razor
  -    let renderer = razor_renderer
  -
       printfn "copying pages to output: %s" output_dir
   
       // copy transformed files to output folder
  
positive.code: 
      let output_dir = config.OutputDir
      let source_dir = config.SourceDir
      // setup output folder
      if Directory.Exists(output_dir) = false then
          Directory.CreateDirectory(output_dir) |> ignore
  
negative.code:         let head = prevposts |> Seq.head
          let pprev = prevposts |> Seq.fold acc head
          pprev
      with
      |_ -> new Page()
  
  