# VendingMachine Example

# Assumptions for a VendingMachine object vm.
# 1. vm only dispenses one type of candy bar.
# 2. A candy bar costs 75 cents (3 quarters).
# 3. If vm runs out of candy bars, throw it away
#    and create another VendingMachine object.
# 4. If you deposit too many quarters, you lose
#    the excess quarters.

class VendingMachine:

    def __init__(self, num_candy_bars):
        self._num_candy_bars = num_candy_bars
        self._num_quarters = 0

    def __str__(self):
        return f"{self._num_candy_bars} {self._num_quarters}"

    def accept_quarter(self):
        self._num_quarters += 1
        print("Quarter accepted.")

    def dispense_candy_bar(self):
        if self._num_quarters >= 3 and \
           self._num_candy_bars > 0:
            
            self._num_candy_bars -= 1
            self._num_quarters = 0
            print("Candy bar dispensed")