First we must make sure we have Sphinx installed:

$ (sudo) pip install sphinx

Also, since this tutorial aims to show how to publish project documentation on ReadTheDocs, then we will also need to download the RTD sphinx theme, as so:

$ (sudo) pip install sphinx-rtd-theme

For the purposes of this tutorial, the simpleble package, which we will be documenting, depends on another package named bluepy. In order for Sphinx to auto-generate documentation from our comments/docstrings, it must also be able to build our package, and thus we must have any dependencies installed and made visible to Sphinx. For this reason, and ONLY for this specific tutorial, we need to install bluepy, as so:

$ (sudo) pip install bluepy

Note that as long as we used the same pip version to install both Sphinx and bluepy, then they will both be added to the same PYTHONPATH, meaning that Sphinx can see blueby (at least on our local machine). A common mistake that people do is to, for example, use pip3 to install one of the two and pip for the other, in which case the above requirement will not be satisfied as the two packages are installed for different versions of Python and thus are added to a different PYTHONPATH.