I am using jupyterhub installed on kubernetes with a docker image(https://jupyterhub.readthedocs.io/en/0.8.0/). I have a requirement to install some custom python packages on jupyterhub so that when a user opens the notebook, he should have the packages available to use without installing it. What is the best way to achieve this? I have heard something called https://jupyterlab.readthedocs.io/en/stable/user/extensions.html. However that seems to be an overkill and it seems like an option to customize the look and feel of notebook itself. My requiremnt is just to make the library available in notebook. I have tried installing the package to the docker image however that did not make the package available in notebook. Please point the direction to proceed