proposition: Lemma pickleP : pcancel pickle unpickle.
proof: Proof. move => s. by elim: s => //= [s -> t ->| s -> | s -> ]. Qed.
imports: Relations mathcomp.ssreflect.ssreflect mathcomp(all_ssreflect) CompDecModal.libs(edone bcase fset base modular_hilbert sltype)