Using the structured analysis draw a context diagram for a credit card system defined below. You should further refine the context diagram to depict more details of the functionality of the system. You are free to make assumptions as needed, but make sure that you have stated them clearly.

The credit card system under consideration handles transactions for retail stores.

For example, a transaction might consist of buying a music CD from your favorite music store (say, HMV). The diagram should include functions for retrieving and checking a credit card record for a customer, approving and recording each transaction, and maintaining a log of transactions for each retail store. The system should maintain files of credit card holders, current transactions, and accounts payable

(approved transactions) for each store.