Definition PcanCountMixin sT f f' (fK : pcancel f f') :=
  @CountMixin sT _ _ (pcan_pickleK fK).Definition CanCountMixin sT f f' (fK : cancel f f') :=
  @PcanCountMixin sT _ _ (can_pcan fK).Definition sub_countMixin P sT := PcanCountMixin (@valK T P sT).Definition pickle_seq s := CodeSeq.code (map (@pickle T) s).Definition unpickle_seq n := Some (pmap (@unpickle T) (CodeSeq.decode n)).

(* Specifications: *)
Lemma pickle_seqK : pcancel pickle_seq unpickle_seq.