Goal:
  
  A : Type
  B : Type
  R : A → B → Type
  R' : ∀ (a : A) (b : B), R a b → Type
  xs : list A
  ys : list B
  a : All2 R xs ys
  a0 : All2_dep R' a
  ============================
   (noConfusionHom_All2_dep_obligation_1 A B R R' xs ys a a0 a0
      (noConfusionHom_All2_dep_obligation_2 A B R R' xs ys a a0 a0 eq_refl) =
    eq_refl)


DEBUG:Going to execute:
try intros until H; intro_block_id H || intro_block H
Level 4: evaluation returns
try intros until H; intro_block_id H || intro_block H;
 (try simpl in H; DepElim.simplify_equations_in H)
where
H := a0
of type
constr of type tacvalue