public function hasUsedThisDiscount(string $discountId): bool 	{ 		return $this->orders()->available()->whereHas('orderItems', function ($query) use ($discountId) { 			$query->whereHas('appliedDiscounts', function ($query) use ($discountId) { 				$query->where('discount_id', $discountId); 			}); 		})->exists(); 	}