-(* unwind_subst metasenv subst *)
-(* unwinds [subst] w.r.t. itself. *)
-(* It can restrict some metavariable in the [metasenv] *)
-val unwind_subst : Cic.metasenv -> substitution -> substitution * Cic.metasenv
+val delift :
+ int -> substitution -> Cic.context -> Cic.metasenv ->
+ (Cic.term option) list -> Cic.term ->
+ Cic.term * Cic.metasenv * substitution