loops

[Verde Denim]

I'm just getting into py coding, and have come across an oddity in a py
book - while loops that don't work as expected...

import random

MIN = 1
MAX = 6

def main():
    again = 'y'

    while again == 'y':
        print('Rolling...')
        print('Values are: ')
        print(random.randint(MIN, MAX))
        print(random.randint(MIN, MAX))

        again = input('Roll again? (y = yes): ')

main()

Produces -
python dice_roll.py
Rolling...
Values are:
5
4
Roll again? (y = yes): y
Traceback (most recent call last):
  File "dice_roll.py", line 17, in <module>
    main()
  File "dice_roll.py", line 15, in main
    again = input('Roll again? (y = yes): ')
  File "<string>", line 1, in <module>
NameError: name 'y' is not defined

This same loop structure appears in many places in this book "Starting
out with Python, 2nd ed, Tony Gaddis), and they all yield the same
error. Is there something I'm missing here?

Thanks for the input...