proposition: Lemma prelift_cons s k x : prelift ((k, x) :: s) = k *: f x + prelift s.
proof: Proof. exact: big_cons. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(fintype bigop order generic_quotient) mathcomp(ssralg ssrnum ssrint)