anchor.diff:                       let eparams = List.map (uncurry (mkVarExp Unmarked)) vs.Params
                        let funcApp = applyFunc ctx funcDecl eparams
   
  -                     Seq.ofList
  -                        // TODO(CaptainHayashi): this needs to be IFF, right?
  -                        [ (ctx.MkImplies (boolToZ3 ctx dex, funcApp),
  -                           ctx.MkSymbol (sprintf "R_%s" vs.Name) :> Z3.Symbol) ] )
  +                     ctx.MkIff (boolToZ3 ctx dex, funcApp))
                   ex
  -            |> withDefault Seq.empty
   
           (mapEntry, rule)
   
  
positive.code:         |> List.unzip
          (* The LHS contains a list of tuples that need to make a map.
             The RHS needs to be filtered for indefinite constraints. *)
          |> pairMap Map.ofSeq Seq.concat
  
      (*
       * Views
  
negative.code:     /// </param>
      /// <returns>
      ///     A tuple of a <c>Map</c> binding names to <c>FuncDecl</c>s and a
      ///     set of <c>BoolExprs</c> asserting view definitions.
      /// </returns>
      let translateViewDefs ctx ds =
          ds
  