Goal:
  
  A : Type
  B : Type
  R : nat → A → B → Type
  n : nat
  b : All2i R n [] []
  b0 := {|
          pr1 := {| pr1 := n; pr2 := {| pr1 := []; pr2 := [] |} |}; pr2 := b
        |}
     : sigma
         (λ index : sigma (λ _ : nat, sigma (λ _ : list A, list B)),
            All2i R (pr1 index) (pr1 (pr2 index)) (pr2 (pr2 index)))
  ============================
   (let H := CoreTactics.block in
    NoConfusionHom_All2i A B R n [] [] All2i_nil b
    → let H0 := CoreTactics.block in All2i_nil = b)


DEBUG:Going to execute:
generalize (eq_refl : v = id'); clearbody id'; simpl in id';
            cont id id' id v