let head_beta_reduce ?delta ?upto t = head_beta_reduce ?delta ?upto t [];;
+type stack_item = RS.stack_term
+type environment_item = RS.env_term
+
+type machine = int * environment_item list * NCic.term * stack_item list
+
+let reduce_machine = R.reduce
+let from_stack = RS.from_stack
+let unwind = R.unwind
+
(* vim:set foldmethod=marker: *)