Goal:
  
  A : Type
  B : Type
  R : nat → A → B → Type
  n : nat
  b : All2i R n [] []
  e : NoConfusionHom_All2i A B R n [] [] All2i_nil b
  ============================
   (let H := CoreTactics.block in
    noConfusionHom_All2i_obligation_2 A B R n [] [] All2i_nil b
      (noConfusionHom_All2i_obligation_1 A B R n [] [] All2i_nil b e) = e)


DEBUG:Going to execute:
CoreTactics.revert_until H
DEBUG LTAC Evaluated term: (let H := CoreTactics.block in
                            noConfusionHom_All2i_obligation_2 A B R n [] []
                              All2i_nil b
                              (noConfusionHom_All2i_obligation_1 A B R n []
                                 [] All2i_nil b e) = e)