anchor.diff:      /// <returns>
       ///     A multiset containing the given items.
       /// </returns>
  -    let ofFlatList xs =
  -        xs |> List.toSeq |> ofFlatSeq
  +    let ofFlatList (xs : List<_>) =
  +        xs |> ofFlatSeq
   
       /// <summary>
       ///     Creates a multiset with one item.
  
positive.code:     ///     A multiset containing the given items.
      /// </returns>
      let ofFlatSeq xs =
          xs
          // First, collate into (k, [k, k, ...]) form...
          |> Seq.groupBy id
          // then, turn into (k, occurences of k).
          |> Seq.map (pairMap id Seq.length)
          |> Map.ofSeq
          |> MSet
  
      /// <summary>
      ///     Creates a multiset with the given flat list as its contents.
  
negative.code:     /// <returns>
      ///     The set of items in the multiset.
      /// </returns>
      let toSet (MSet ms) =
          Map.fold (fun set k n -> Set.add k set) Set.empty ms
  
      (*
       * Operations
  