Inventory Stock Report

A shop's Inventory keeps its stock in a dictionary that maps item names to quantities.

Part 1: Inventory()

A new inventory has an empty dictionary in stock.

• add(item, quantity) adds to that item's quantity. A new item starts from 0.
• remove(item, quantity):
  • if the item isn't stocked, or there's less than quantity of it, change nothing and return False,
  • otherwise take the quantity away and return True. If an item's quantity drops to 0, delete it from stock.
• count(item) returns how many of that item there are. An item that isn't stocked gives 0.
• __repr__ returns Inventory(name=qty, name=qty) with items in alphabetical order, separated by ", ". An empty inventory is Inventory().

Part 2: stock_report(moves)

Make an inventory. moves is a list of (action, item, quantity) tuples, where action is "add" or "remove". Apply them in order. Return [str(inventory), number of failed removes].