fact: Fixpoint dep_value_aux (n: nat): dep_type n -> dep_type n := match n return dep_type n -> dep_type n with | 0 => fun x => x.+1 | 1 => fun x => ~~x | n'.+2 => dep_value_aux n' end.
imports: mathcomp(ssreflect ssrbool ssrnat eqtype seq)