The Cellar Ledger of the Rusty Tankard

The cellarer of the Rusty Tankard keeps a ledger of what sits in the cellar: each barrel name written beside the number of measures left in it. Barrels that have been drained are not always struck out — some still sit in the ledger with a nought beside them — and casks the inn has never carried are simply absent.

Each morning the cook hands over a list of names to check before the market opens.

Write outOfStock(stock, wanted), where:

• stock is a dictionary (object) whose keys are barrel names (strings) and whose values are the measures remaining (non-negative integers).
• wanted is a list (array) of barrel names (strings). It contains no repeated names, and may be empty.

Return a new list of the names from wanted that the inn cannot serve: a name counts as unservable if it does not appear as a key in stock, or if it appears with a value of 0. The returned names must be in the same order as they appear in wanted. If every wanted name is servable, return an empty list.