Goal:
    A : Type  B : Type  R : nat → A → B → Type  n : nat  H : True
  ============================
   (All2i_nil = All2i_nil)


DEBUG:Going to execute:
DepElim.do_depelim_nosimpl tac H; DepElim.simpl_dep_elim;
            CoreTactics.unblock_goal