sample.py

def build_book_inventory(book_ids, shops):
    shop_labels = [shop['label'] for shop in shops]
    book_list = Persistency.books_table.read(
	shops=shop_labels,
	books=book_ids)
    inventory = {}
    for book_item in book_list:
	shop_label = book_item['shop_label']
	cell_label = book_item['cell_label']
	book_id = book_item['book_id']
	count = book_item['count']
	if shop_label not in inventory:
	    inventory[shop_label] = {}
	if cell_label not in inventory[shop_label]:
	    inventory[shop_label][cell_label] = {}
	inventory[shop_label][cell_label][book_id] = count
    return inventory