Create context diagram and level$-0$ diagram$($gane and sarson$)$ :

Picnics R Us $($PRU$)$ is a small catering firm with five employees. During a typical summer weekend, PRU caters for $15$ picnics with $20-50$ people each. The business has grown rapidly over the past year and the owner wants to install a new computer system for managing the ordering and buying process. PRU has a set of $10$ standard picknick packages $($e$.$g$.,$ a $$Sandwich Platter$$ or $$Burgers in the Park$).$ When potential customers call, the receptionist describes the packages to them. If the customer decides to book a picnic, the receptionist records the customer information $($e$.$g$.,$ name, address, phone number, etc.$)$ and the information about the picnic $($e$.$g$.,$ place, date, time, which one of the standard packages, total price$)$ on a contract. The customer is then emailed a copy of the contract and must sign and return it along with the payment $($often a credit card or by check$)$ before the picnic is officially booked. Sometimes, the customer wants something special $($e$.$g$.,$ birthday cake$).$ In this case, the receptionist takes the information and gives it to the owner who determines the cost; the receptionist then calls the customer back with the price information. Sometimes the customer accepts the price; other times, the customer requests some changes which have to go back to the owner for a new cost estimate. The owner would like to use the system for marketing as well. It should be able to track how customers learned about PRU and identify repeat customers, so that PRU can send them special offers.