Construct a vending machine controller implemented as a MEALY state machine. The vending machine has the following features. $$ The vending machine stocks four selections, A $($M&Ms$),$ B $($Doritos$),$ C $($Baby Ruth$)$ and D $($Pop Tarts$).$ The prices of the selections are shown in Table $1.$ The vending machine accepts only one type of coin: nickels. $$ The vending machine gives back change if the price of a selection is exceeded. $$ If at any time the customer presses the Coin Return button all accumulated monies are returned.