Code review and docstrings conventions

[kuchaale]

Motivated by today discussion, this issue is intended to improve the readability of our code and make it consistent across the wide spectrum of Python code.

Let's happen our code to be PEP 8 and PEP 257 compliant. The former can be done using the Black formatter (or Jupyterlab Code Formatter) for instance. The latter must be done manually.