proposition: Lemma le_fix_order (x y : T) : y \in iterF (fix_order x) -> fix_order y <= fix_order x.
proof: Proof. exact: fix_order_small. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat div seq) mathcomp(choice fintype finfun bigop)