proposition: Lemma liftP A (x : lift A) : lift_spec x x.
proof: Proof. by case: x=>[|a]; [apply: undef_spec | apply: up_spec]. Qed.
imports: Coq(ssreflect ssrbool ssrfun) mathcomp(ssrnat eqtype) pcm(options prelude) pcm(pcm morphism)