Goal:
    A : Type  B : Type  R : nat → A → B → Type  n : nat
  ============================
   (let H := CoreTactics.block in All2i_nil = All2i_nil)


DEBUG:Going to execute:
CoreTactics.intros_until_block
DEBUG LTAC Evaluated term: (let H := CoreTactics.block in
                            All2i_nil = All2i_nil)