Goal:
  
  A : Type
  P : list A → A → Type
  Q : list A → list A → A → A → Type
  d : A
  Γ : list A
  d0 : A
  Γ0 : list A
  hlen : #|d :: Γ| = #|d0 :: Γ0|
  ============================
   (All_fold P Γ
    → P Γ d
      → All_fold P Γ0
        → P Γ0 d0
          → (∀ (Δ Δ' : list A) (x y : A),
               All_fold P Δ
               → All_fold P Δ'
                 → All2_fold Q Δ Δ' → P Δ x → P Δ' y → Q Δ Δ' x y)
            → (∀ Δ : list A, #|Γ| = #|Δ| → All_fold P Δ → All2_fold Q Γ Δ)
              → let H := CoreTactics.block in All2_fold Q Γ Γ0)


DEBUG:Going to execute:
CoreTactics.block_goal
Level 34: evaluation returns
idtac of type tacvalue

Level 32: evaluation returns
idtac of type tacvalue

Level 31: evaluation returns
idtac of type tacvalue

Level 29: evaluation returns
idtac of type tacvalue

Level 27: evaluation returns
idtac of type tacvalue

Level 26: evaluation returns
idtac of type tacvalue

Level 24: evaluation returns
idtac of type tacvalue

Level 22: evaluation returns
idtac of type tacvalue

Level 21: evaluation returns
idtac of type tacvalue

Level 19: evaluation returns
idtac of type tacvalue

Level 17: evaluation returns
idtac of type tacvalue

Level 16: evaluation returns
idtac of type tacvalue

Level 14: evaluation returns
idtac of type tacvalue

Level 12: evaluation returns
idtac of type tacvalue

Level 11: evaluation returns
idtac of type tacvalue

Level 9: evaluation returns
idtac of type tacvalue

Level 7: evaluation returns
idtac of type tacvalue

Level 6: evaluation returns
idtac of type tacvalue

Level 4: evaluation returns
idtac of type tacvalue

Level 2: evaluation returns
idtac of type tacvalue

Level 1: evaluation returns
idtac of type tacvalue