Add double-quoted strings

[fur] / examples / 14_boolean_operators.fur

print('false and false: ')
print(false and false)
print('\n')
print('false and true: ')
print(false and true)
print('\n')
print('true and false: ')
print(true and false)
print('\n')
print('true and true: ')
print(true and true)
print('\n')
print('false or false: ')
print(false or false)
print('\n')
print('false or true: ')
print(false or true)
print('\n')
print('true or false: ')
print(true or false)
print('\n')
print('true or true: ')
print(true or true)