fact: Definition bseq_tagged_tuple n T (s : n.-bseq T) : {k : 'I_n.+1 & k.-tuple T} := Tagged _ (in_tuple s : (Ordinal (size_bseq s : size s < n.+1)).-tuple _).
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat) mathcomp(seq choice fintype path)