~unify:(fun m s c t1 t2 ->
try Some (NCicUnification.unify status m s c t1 t2)
with NCicUnification.UnificationFailure _ | NCicUnification.Uncertain _ -> None)
~unify:(fun m s c t1 t2 ->
try Some (NCicUnification.unify status m s c t1 t2)
with NCicUnification.UnificationFailure _ | NCicUnification.Uncertain _ -> None)