>>> x, y, z = 10, 20, 30
>>> x
10
>>> y
20
>>> z
30
>>> x = 10
>>> del x
>>> x
Traceback (most recent call last):
File "<pyshell#2>", line 1, in <module>
x
NameError: name 'x' is not defined
>>>
>>> x = None
>>> print(x)
None
>>> x
>>> (아무것도 출력되지 않음)
>>> x = -10
>>> +x
-10
>>> -x
10