anchor.diff:                  mapMessages ModelFilterError npmNoSymbolicConstraintsR)
   
       let symproof : Result<Model<_, _>, Error> -> Result<Model<_, _>, Error> =
  -        bind (Core.Instantiate.Phase.run approx
  +        bind (Core.Instantiate.Phase.run shouldApprox
                 >> mapMessages Error.ModelFilterError)
       let eliminate : Result<Model<_, _>, Error> -> Result<Model<_, _>, Error>  =
  -        lift (Backends.Z3.eliminate reals)
  +        lift (Backends.Z3.eliminate shouldUseRealsForInts)
   
       let backend m =
           let phase op response =
  
positive.code:     // Shorthand for the various stages available.
      let hsf = bind (Backends.Horn.hsfModel >> mapMessages Error.HSF)
      let smt rq = lift (Backends.Z3.backend rq)
      let muz3 rq = bind (Backends.MuZ3.run reals rq >> mapMessages Error.MuZ3)
      let frontend times rq =
          Lang.Frontend.run times rq Response.Frontend Error.Frontend
      let graphOptimise =
  
negative.code:         |> Optimiser.Utils.parseOptimisationString
  
      let bp = backendParams ()
      let { Approx = shouldApprox
            NoSMTReduce = noSMTReduce
            Reals = shouldUseRealsForInts } =
          config.backendOpts
          |> maybe (Seq.empty) Utils.parseOptionString
          |> Seq.fold
  