Utils: inventory

Inventory manipulation helpers.

add_item(inventory, item_id)

Return a new inventory with item_id added.

all_keys_with_id(inventory, key_store, key_id)

Return persistent set of all key IDs matching key_id.

has_key_with_id(inventory, key_store, key_id)

Return ID of a key with key_id if present in inventory else None.

remove_item(inventory, item_id)

Return a new inventory with item_id removed.