Goal:
    A : Type  P : list A → A → Type  l : list A  a : All_fold P l
  ============================
   (let H := CoreTactics.block in
    let H0 := CoreTactics.block in
    noConfusionHom_All_fold_obligation_1 A P l a a
      (noConfusionHom_All_fold_obligation_2 A P l a a eq_refl) = eq_refl)


DEBUG:Going to execute:
fun p el => destruct p using el