anchor.diff:                       MuSat.Sat (fixedpoint.GetAnswer ())
                    | Z3.Status.UNSATISFIABLE ->
                        MuSat.Unsat (fixedpoint.GetAnswer ())
  -                 | _ -> MuSat.Unknown)
  +                 | Z3.Status.UNKNOWN ->
  +                     MuSat.Unknown (fixedpoint.GetReasonUnknown ())
  +                 | _ -> MuSat.Unknown "query result out of bounds")
               fm
   
   
  
positive.code:         /// <summary>
          ///     The proof gave an odd result.
          /// </summary>
          | Unknown
  
      /// <summary>
      ///     A MuZ3 model.
  
negative.code:     /// Pretty-prints a MuSat.
      let printMuSat =
          function
          | MuSat.Sat ex -> colonSep [ String "sat" ; printZ3Exp ex ]
          | MuSat.Unsat ex -> colonSep [ String "unsat" ; printZ3Exp ex ]
          | MuSat.Unknown reason -> colonSep [ String "unknown" ; String reason ]
      
      /// Pretty-prints a MuModel.
      let printMuModel { Assertions = ts ; Rules = rs ; FuncDecls = fdm } =
  