NCic.metasenv -> NCic.context -> NCic.term option ->
NCic.metasenv * NCic.term * NCic.term (* menv, instance, type *)
+(* returns the resulting type, the metasenv and the arguments *)
val saturate:
?delta:int -> NCic.metasenv -> NCic.context -> NCic.term -> int ->
NCic.term * NCic.metasenv * NCic.term list