You can access the source code of any module that you use in two ways. First, go to the module page at github.com and view all the files, releases, commits, and issues in one place, as in the following screenshot. I have read access to all shared code via the netmiko module maintainer and can see a full list of commits and file contents:
The second method is to install the package itself in the Python site-package directory using pip or PyCharm GUI. What pip actually does is it goes to GitHub and downloads the module content and runs setup.py to install and register the module. You can see the module files, but this time you have full read/write access on all files and you can change the original code. For example, the following code leverages the netmiko library to connect to a Cisco device and execute the show arp command on it:
from netmiko import...