Develop an Petri Nets based on the following narrative. If you need to make assumptions, you can do. (Marks: 12.5)

The shipping department receives all shipments on outstanding purchase orders. When the clerk in the shipping department receives a shipment, he or she finds the outstanding purchase order for those items. The clerk then sends multiple copies of the shipment packing slip. One copy goes to purchasing, and the department updates its records to indicate that the purchase order has been fulfilled. Another copy goes to accounting so that a payment can be made. A third copy goes to the requesting in-house customer so that he or she can receive the shipment. Once payment is made, the accounting department sends a notification to be purchasing once the customer receives and accepts the goods, he or she sends notification to be purchasing. When purchasing receives these other verifications, it closes the purchase order as fulfilled and paid