let mk_fresh_name_callback = FreshNamesGenerator.mk_fresh_name ~subst:[] in
let term = C.Sort C.Set in
let letout_tac (proof, goal) =
let mk_fresh_name_callback = FreshNamesGenerator.mk_fresh_name ~subst:[] in
let term = C.Sort C.Set in
let letout_tac (proof, goal) =