unfold ListHybrid_G, G_hybrid.
comp_skip.
comp_simp.
eapply comp_spec_eq_impl_eq.
simpl.
comp_simp.
simpl.
eapply comp_spec_eq_refl.
Qed.

Theorem skipn_ge_nil :
forall (A : Type)(ls : list A)(n : nat),
n >= length ls ->
skipn n ls = nil.