proposition: Lemma fset0I A : fset0 `&` A = fset0.
proof: Proof. by apply/fsetP => x; rewrite !inE andFb. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrnat eqtype ssrfun seq) mathcomp(choice path finset finfun fintype bigop)