Goal:
    A : Type  l : list A  hd : A  tl : list A
  ============================
   (Some hd = Some hd ∧ tl = tl)


DEBUG:Going to execute:
intros; Zify.zify_pre_hook; zify_elim_let; zify_op;
            Zify.zify_iter_specs; Zify.zify_to_euclidean_division_equations