fact: Definition unify_cumul@{a b+} (A : Type@{a}) (B : Type@{b}) (U : Unification) : t (moption (A->B)) := unify_cumul_cnt U A B (fun f => M.ret (mSome f)) (M.ret mNone).
imports: Strings.String NArith.BinNat Mtac2(Logic Datatypes Logic List Utils MTele Pattern Specif)