+val rewritingstep : (string option * NTacStatus.tactic_term) option -> NTacStatus.tactic_term ->
+ [ `Term of NTacStatus.tactic_term | `Auto of NnAuto.auto_params
+ | `Proof | `SolveWith of NTacStatus.tactic_term ] ->
+ bool (* last step *) -> 's NTacStatus.tactic
+val print_stack : 's NTacStatus.tactic