proposition: Lemma restrictf_id f A : [disjoint domf f & A] -> f.[& A] = [fmap].
proof: Proof. by move=> dAf; rewrite restrictf_mkdom (eqP dAf) restrictf0. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrnat eqtype ssrfun seq) mathcomp(choice path finset finfun fintype bigop)