Prepare a DFD fragment for the following: Toy Wholesaler, Inc. (TWI) purchases toys from various toy manufacturers and resells the toys to local retail shops. TWI's supervisors have given you the following information with regard to part of its information system. A purchase requisition is sent from the inventory system and is received by Tom Piper, a clerk in the Purchasing department. Tom prepares a purchase order from information in the vendor and inventory files and mails it to the vendor. The vendor returns a vendor acknowledgement to Tom indicating the receipt of the purchase order. Tom then sends a purchase order notification to Mary Contrary, a clerk in the Accounts Payable department.