anchor.diff:          with get () : IntSet =
               IntSet Empty
   
  +    //
  +    member private __.Trie
  +        with get () = trie
  +
       /// The number of elements in the IntSet.
       member __.Count
           with get () : int =
  
positive.code:         set.Contains key
  
      //
      [<CompiledName("OfSeq")>]
      let inline ofSeq source : IntSet =
          // Preconditions are checked by the member.
  
negative.code:         set.Contains (int key)
  
      //
      [<CompiledName("Union")>]
      let inline union (set1 : TagSet<'Tag>) (set2 : TagSet<'Tag>) : TagSet<'Tag> =
          // Retype as IntSet
          let set1 : IntSet = retype set1
          let set2 : IntSet = retype set2
  
          // Preconditions
          checkNonNull "set1" set1
          checkNonNull "set2" set2
  
          set1.Union set2
          |> retype
  
      //
      [<CompiledName("OfSeq")>]
      let inline ofSeq source : TagSet<'Tag> =
          // Preconditions are checked by the member.
  