roblem $5[13$ pts $(5,4,4)]$: Vending Machine

Consider the construction of a vending machine$$s logic. Assume that every soda costs a quarter,

and that the machine accepts only quarters.

$$ E $=$ True indicates the machine is empty, it has no more sodas

$$ S $=$ True indicates the user has made a selection

$$ P $=$ True indicates the user has paid a quarter

The machine may send two control commands to its machinery:

$$ V $=$ True indicates machine will give the user a soda $($i$.$e$.$vend$)$

$$ R $=$ True indicates machine will return the user$$s quarter