The function count_items consumes a GroceryList instance and produces the total number of items that are in the grocery list. A GroceryList is a dataclass with three integer fields: eggs, bread, and milk.

When counting up the items of a grocery list, you need to multiply the eggs by 12 (since one package contains a dozen eggs) and the bread by 20 (since one loaf contains about 20 slices).

One unit test is provided to you, but you should write another!