'string.join' is wrong in my Python console

[Robert]

Hi,

I read the tutorial on "Why is join() a string method instead of a list
 or tuple method?"
at link:
https://docs.python.org/2/faq/design.html#why-must-self-be-used-explicitly-in-method-definitions-and-calls

I have a problem on running the last line:
---------------
If none of these arguments persuade you, then for the moment you can
 continue to use the join() function from the string module, which allows
 you to write

string.join(['1', '2', '4', '8', '16'], ", ")
-----------------------

My Python console is 2.7. It should be no problem because I see the tutorial
is 2.7 too.

The console has these display:

string.join(['1', '2', '4', '8', '16'], ", ")
---------------------------------------------------------------------------
NameError                                 Traceback (most recent call last)
<ipython-input-15-3947890a7e6e> in <module>()
----> 1 string.join(['1', '2', '4', '8', '16'], ", ")

NameError: name 'string' is not defined 


>From the context, I don't see string should be replaced by something else.

Could you tell me why I have such an error?


Thanks,