The finance team wants every price change on record. The table price_log is ready: product_id, old_price, new_price, and changed_at, which fills itself with the current time.

1. Create the trigger function log_price_change(). It adds one row to price_log with the product's id, its old price and its new price.
2. Create the trigger log_price. It runs your function after each update of a row in products.
3. The Kraken Plush (product 1) now costs 31.99. Change it.
4. Think before you run it: the stickers (category 3) all get 0.50 more expensive. How many rows will price_log hold after that change?
5. Raise the price of every product in category 3 by 0.50.