Python version, "2.7.2+", what does the plus sign mean?

Question

I have a virtual environment that I installed some time ago. When I activate it and run python, they tell me the version number

Python 2.7.2+ (default, Oct 4 2011, 20:03:08) 

What does the plus after version number mean?

And can this somehow explain why the os.urandom function os.urandom not defined, even if (according to the documentation ), it has been there since version 2.4.

 >>> from os import urandom Traceback (most recent call last): File "<stdin>", line 1, in <module> ImportError: cannot import name urandom 

Answer 1

From the effbot Python versioning scheme guide :

You can also find version numbers with the suffix "+", for example. "2.2+". These are unreleased versions created directly from the subversive activities of the trunk. In practice, after the final minor release is made, the subversion trunk is added to the next minor version, which becomes version "a0", for example. "2.4a0".

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And for your second question, the inability to import urandom into virtualenv is a known issue.

This answer to a similar question should be helpful.