fact: Definition widen_bseq m n (lemn : m <= n) (bs : m.-bseq T) : n.-bseq T := @Bseq n T bs (leq_trans (size_bseq bs) lemn).
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat) mathcomp(seq choice fintype path)