proposition: Corollary slice_usize s : s = &:s `]-oo, size s[.
proof: Proof. by rewrite itv_overR /=; [rewrite slice_uu | rewrite addn0]. Qed.
imports: Coq(ssreflect ssrbool ssrfun) mathcomp(ssrnat eqtype seq path interval order) pcm(options prelude ordtype seqext)