anchor.diff:              mview
               m
       | Z3 z -> Backends.Z3.Pretty.printResponse mview z
  +    | SymZ3 (z, m) ->
  +       headed "SymZ3 result:" [ Backends.Z3.Pretty.printResponse mview z ;  
  +                      (printModelView
  +                        (printTerm printSMBoolExpr printSMBoolExpr printSMBoolExpr)
  +                        (fun _ -> Seq.empty)
  +                        mview
  +                        m) ] 
       | MuZ3 z -> Backends.MuZ3.Pretty.printResponse mview z
       | HSF h -> Backends.Horn.Pretty.printHorns h
   
  
positive.code:         | Request.Z3 rq       -> phase (symproof >> proof approx >> z3 reals rq) Response.Z3
          | Request.HSF         -> phase (filterIndefinite >> hsf) Response.HSF
          | Request.MuZ3 rq     -> phase (filterIndefinite >> muz3 reals rq) Response.MuZ3
          | _                   -> fail (Error.Other "Internal")
  
      //Build a phase with
  
negative.code:     | Proof
      /// Output a fully-instantiated unstructured proof without symbols.
      | RawProof
      /// Run the Z3 backend, with the given request.
      | SymZ3 of Backends.Z3.Types.Request
      /// Run the Z3 backend, with the given request.
      | Z3 of Backends.Z3.Types.Request
      /// Run the MuZ3 backend (experimental), with the given request.
  