fact: Definition tagged_tuple_bseq n T (t : {k : 'I_n.+1 & k.-tuple T}) : n.-bseq T := widen_bseq (leq_ord (tag t)) (tagged t).
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat) mathcomp(seq choice fintype path)