Goal:
  
  A : Type
  B : Type
  R : nat → A → B → Type
  n : nat
  x : A
  y : B
  l : list A
  r : list B
  r0 : R n x y
  a : All2i R (S n) l r
  ============================
   (let H := CoreTactics.block in
    let H0 := CoreTactics.block in
    noConfusionHom_All2i_obligation_1 A B R n (x :: l) 
      (y :: r) (All2i_cons r0 a) (All2i_cons r0 a)
      (noConfusionHom_All2i_obligation_2 A B R n (x :: l) 
         (y :: r) (All2i_cons r0 a) (All2i_cons r0 a) eq_refl) = eq_refl)


DEBUG:Going to execute:
PTRDEBUGTACchange T; CoreTactics.intros_until_block
Level 6: T
 has value 
(let H := CoreTactics.block in
 noConfusionHom_All2i_obligation_1 A B R n (x :: l) 
   (y :: r) (All2i_cons r0 a) (All2i_cons r0 a)
   (noConfusionHom_All2i_obligation_2 A B R n (x :: l) 
      (y :: r) (All2i_cons r0 a) (All2i_cons r0 a) eq_refl) = eq_refl)