What was the file that has rot13 coding in Python and what was the name?

Question

I remember that there was a file in Python something.py that has rot13 coding. It has for loops and variables like d,c etc. Can anyone tell me that the name of that file and where is it in Python 3.5?

Edit: It's a module coming with Python, not 3rd party.

Answer 1

PEP-20 :

import this
print(this.s)

The source code can be found at:

https://github.com/python/cpython/blob/master/Lib/this.py