if len(''):
    print('0 is treated as True')
else:
    print('0 is treated as False') # executed
    
if -1:
    print('-1 is treated as True') # executed
else:
    print('-1 is treated as False')
    
if 1:
    print('of course, True') # executed
else:
    print('what?')
print(bool(0)) # False
print(bool(-1)) # True
print(bool(1)) # True