anchor.diff:          .References(fun r ->
               [
                   r.NuGet("IntelliFactory.Reactive").Reference()
  +                r.NuGet("WebSharper.Html").Reference()
                   r.Project(main)
               ])
   
  
positive.code: let bt =
      BuildTool().PackageId("WebSharper.Piglets")
          .VersionFrom("WebSharper")
          .WithFramework(fun fw -> fw.Net40)
  
  let main =
  
negative.code:         .SourcesFromProject()
          .References(fun r ->
              [
                  r.NuGet("IntelliFactory.Reactive").ForceFoundVersion().Reference()
                  r.NuGet("WebSharper.Html").ForceFoundVersion().Reference()
              ])
  
  let test =
  