anchor.diff:  open System.IO
   open System.Collections.Generic
   open Paket.PackageSources
  +open System.Text.RegularExpressions
   
   /// Downloads and extracts all packages.
   let ExtractPackages(sources,force, packages:PackageResolution) = 
  
positive.code: 
  let private copyContentFilesToProject (project : ProjectFile) packagesWithContent = 
  
      let blackList (fi : FileInfo) = 
          let rules : list<(FileInfo -> bool)> = [
              fun f -> f.Name <> "_._"
          ]
          rules
          |> List.forall (fun rule -> rule(fi))
  
      let rec copyDirContents (fromDir : DirectoryInfo, toDir : Lazy<DirectoryInfo>) =
          fromDir.GetDirectories() |> Array.toList
  
negative.code:         |> List.append
              (fromDir.GetFiles() 
                  |> Array.toList
                  |> List.filter (onBlackList >> not)
                  |> List.map (fun file -> file.CopyTo(Path.Combine(toDir.Force().FullName, file.Name), true)))
  
      packagesWithContent
  