proposition: Lemma fpowerset0 : fpowerset fset0 = [fset fset0].
proof: Proof. by apply/fsetP=> X; rewrite inE fpowersetE fsubset0. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrnat eqtype ssrfun seq) mathcomp(choice path finset finfun fintype bigop)