anchor.diff:          with _ -> None
       let firstWithName localName (els: XElement seq) =
           els |> Seq.find (fun x -> x.Name.LocalName = localName)
  +    let tryFirstWithName localName (els: XElement seq) =
  +        els |> Seq.tryFind (fun x -> x.Name.LocalName = localName)
       let elements (el: XElement) =
           el.Elements()
       let attr name (el: XElement) =
  
positive.code:                 metadata.Elements()
                  |> firstWithName "dependencies" |> elements
                  // We don't consider different frameworks
                  |> firstWithName "group" |> elements
                  |> Seq.map (attr "id")
                  |> Seq.filter (isSystemPackage >> not)
                  |> Set
  
negative.code:     else
          let rootDir = IO.Path.Combine(IO.Path.GetDirectoryName(dllPath), "..", "..")
          let fableDir = IO.Path.Combine(rootDir, "fable")
          let firstGroupOrAllDependencies (dependencies: XElement seq) =
              match tryFirstWithName "group" dependencies with
              | Some firstGroup -> elements firstGroup
              | None -> dependencies
          match tryFileWithPattern rootDir "*.nuspec",
                tryFileWithPattern fableDir "*.fsproj" with
          | Some nuspecPath, Some fsprojPath ->
  