raising errors — making your code fail loudly on purpose

Last drill. Write a tiny order system:

1. Define a custom exception class OutOfStock that inherits from Exception.
2. Define a function place_order(inventory, item, qty) that:
   • Raises KeyError(item) if item is not in inventory.
   • Raises OutOfStock(f"only {inventory[item]} left of {item}") if inventory[item] < qty.
   • Otherwise returns the string f"shipped {qty} {item}".
3. Loop over three orders. For each, wrap the call in try/except (KeyError, OutOfStock) as err: print(err).

Use this inventory and these orders:

inventory = {"book": 5, "pen": 0}
orders = [("book", 2), ("pen", 1), ("hat", 1)]

Expected output:

shipped 2 book
only 0 left of pen
'hat'