anchor.diff:  type DistinctBy() =
       inherit Default1()
       static member val Instance = DistinctBy()
  -    [<Extension>]static member        DistinctBy (x:seq<'T>    , f, [<Optional>]impl:Default2  ) = Seq.distinctBy f x
       [<Extension>]static member inline DistinctBy (x:'Foldable'T, f, [<Optional>]impl:Default1  ) = x |> ToSeq.Invoke |> Seq.distinctBy f |> FromSeq.Invoke :'Foldable'T
       [<Extension>]static member        DistinctBy (x:list<'T>   , f, [<Optional>]impl:DistinctBy) = Seq.distinctBy f x |> Seq.toList
       [<Extension>]static member        DistinctBy (x:'T []      , f, [<Optional>]impl:DistinctBy) = Seq.distinctBy f x |> Seq.toArray
  
positive.code: [<Extension;Sealed>]
  type Take() =
      static member val Instance = Take()
      [<Extension>]static member        Take (x:seq<'a>       , n, [<Optional>]impl:Default2) = Seq.take n x
      [<Extension>]static member inline Take (x:'Foldable'T   , n, [<Optional>]impl:Default1) = x |> ToSeq.Invoke |> Seq.take n |> FromSeq.Invoke :'Foldable'T
      [<Extension>]static member        Take (x:string        , n, [<Optional>]impl:Take    ) = x.[..n-1]
      [<Extension>]static member        Take (x:StringBuilder , n, [<Optional>]impl:Take    ) = new StringBuilder(x.ToString().[..n-1])
  
negative.code: type SortBy() =
      inherit Default1()
      static member val Instance = SortBy()
      [<Extension>]static member inline SortBy (x:'Foldable'T, f      , [<Optional>]impl:Default1) = x |> ToSeq.Invoke |> Seq.sortBy f |> FromSeq.Invoke :'Foldable'T
      [<Extension>]static member        SortBy (x:list<'a>   , f      , [<Optional>]impl:SortBy  ) = List.sortBy  f x
      [<Extension>]static member        SortBy (x:'a []      , f      , [<Optional>]impl:SortBy  ) = Array.sortBy f x
  