Added type annotations for this library, as well as fixed issues regarding Sphinx documentation formatting. Thanks tcfranks!
To use in CircuitPython, simply install the [Adafruit CircuitPython Bundle](https://circuitpython.org/libraries).
To use in CPython, `pip3 install adafruit-circuitpython-pcf8591`.
Read the [docs](http://circuitpython.readthedocs.io/projects/pcf8591/en/latest/) for info on how to use it.