You may follow the quick steps below in order to get a list of all the modules installed in Python:
(1) To start, open the Python Shell and then type/copy this command:
help('modules')
This is how the command would look like in the Python Shell:
(2) Finally, press ENTER, and you would get the list of all the modules installed/available in Python. Here is a glance of the modules installed in my case:
You may also want to check the following source that explains the complete steps to install a module in Python.