anchor.diff:  
   [<Extension;Sealed>]
   type Item1 =
  -    static member inline       Item1 (t :'a          ) = (^a : (member Item1: _ ) t)
       [<Extension>]static member Item1 ((a, _, _, _, _)) = a
       [<Extension>]static member Item1 ((a, _, _, _)   ) = a
       [<Extension>]static member Item1 ((a, _, _)      ) = a
  
positive.code: 
  [<Extension;Sealed>]
  type Item4 =
      static member inline       Item4 (t :'a          ) = (^a : (member Item4: _ ) t)
      [<Extension>]static member Item4 ((_, _, _, d, _)) = d
      [<Extension>]static member Item4 ((_, _, _, d)   ) = d
  
  
negative.code: 
  [<Extension;Sealed>]
  type Item2 =
      [<Extension>]static member Item2 ((_, b, _, _, _)) = b
      [<Extension>]static member Item2 ((_, b, _, _)   ) = b
      [<Extension>]static member Item2 ((_, b, _)      ) = b
  