Write a program that keeps vegetable names and prices in a dictionary as key-value pairs. The program should display a menu that lets the user see a list of all vegetables and their prices, add a new vegetable and price, change the price of an existing vegetable, and delete an existing vegetable and price. The program should pickle the dictionary and save it to a file when the user exits the program (Use pickle module to save and restore file in binary). Each time the program starts, it should retrieve the dictionary from the file and unpickle it.