Draw a use case diagram for the following situation (state any assumptions you believe you have to make in order to develop a complete diagram). Then convert the use case diagram into a sequence diagram. Stillwater Antiques buys and sells one-of-a-kind antiques of all kinds (e.g., furniture, jewelry, china, and clothing). Each item is uniquely identified by an item number and is also characterized by a description, an asking price, and a condition as well as open-ended comments. Stillwater works with many different individuals, called clients, who sell items to and buy items from the store. Some clients only sell items to Stillwater, some only buy items, and others both sell and buy. A client is identified by a client number and is also described by a client name and client address. When Stillwater sells an item in stock to a client, the owners want to record the commission paid, the actual selling price, the sales tax (tax of zero indicates a tax-exempt sale), and the date the item sold. When Stillwater buys an item from a client, the owners want to record the purchase cost, the purchase date, and the condition of the item at the time of purchase.