proposition: Lemma restrictfT f : f.[& domf f] = f.
proof: Proof. by apply/fmapP=> k; rewrite fnd_restrict; case: fndP. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrnat eqtype ssrfun seq) mathcomp(choice path finset finfun fintype bigop)