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