I discovered the built-in `help()` recently that prints some information for a module, function, method, class, etc. But where exactly does it find the information it shows? [Python docs](https://docs.python.org/2/library/functions.html#help) don't give a single hint about this.

```
>>> import base64
>>> help(base64)
Help on module base64:

NAME
    base64 - RFC 3548: Base16, Base32, Base64 Data Encodings

FILE
    /usr/lib/python2.7/base64.py
..

```