Goal:
    A : Type  B : Type  C : Type  R : A → B → C → Type  b : All3 R [] [] []
  ============================
   (∀ e : NoConfusionHom_All3 A B C R [] [] [] All3_nil b,
      let H := CoreTactics.block in
      noConfusionHom_All3_obligation_2 A B C R [] [] [] All3_nil b
        (noConfusionHom_All3_obligation_1 A B C R [] [] [] All3_nil b e) = e)


DEBUG:Going to execute:
fun id =>
             CoreTactics.on_last_hyp
              ltac:(fun id' =>
                      match id' with
                      | id => idtac
                      | _ => revert id'; CoreTactics.revert_until id
                      end)