Goal:
    A : Type  B : Type  C : Type  R : A → B → C → Type
  ============================
   (∀ (H := CoreTactics.block) (e : NoConfusionHom_All3 A B C R [] [] []
                                      All3_nil All3_nil),
      let H0 := CoreTactics.block in
      noConfusionHom_All3_obligation_2 A B C R [] [] [] All3_nil All3_nil
        (noConfusionHom_All3_obligation_1 A B C R [] [] [] All3_nil All3_nil
           e) = e)


DEBUG:Going to execute:
match T with
           | context [ CoreTactics.block ] =>
               change T; CoreTactics.intros_until_block
           end