Below is an context that describes a sql query, paired with an question that provides further information. Write an answer that appropriately completes the request.  # noqa: E501
### Context:
CREATE TABLE products_booked (product_id VARCHAR)
### Question:
What is the id of the product that is booked for 3 times?
### Answer:
SELECT product_id FROM products_booked GROUP BY product_id HAVING COUNT(*) = 3