main.py

import library.sol as lib

# Main loop
while True:
    print('=' * 21)
    print('Library System')
    print('=' * 21)
    print('1. Add books to the library')
    print('2. Check out a book')
    print('3. Return a book')
    print('4. View library status')
    print('Q. Quit')
    m = input('Select an option from above or enter Q to quit. ')
    if m.upper() == 'Q':
        break

    # replace 'pass' with appropriate inputs and function calls.
    elif m == '1':
        pass
    elif m == '2':
        pass
    elif m == '3':
        pass
    elif m == '4':
        pass
    else:
        print('Invalid selection.')