Goal:
    A : Type  P : list A → A → Type
  ============================
   (let H := CoreTactics.block in All_fold_nil P = All_fold_nil P)


DEBUG:Going to execute:
CoreTactics.intros_until_block
DEBUG LTAC Evaluated term: (let H := CoreTactics.block in
                            All_fold_nil P = All_fold_nil P)