Use idiomatic Python throughout the examples

To improve example readability and improve familiarity to Pythonistas, we should use idiomatic Python throughout the examples. In the past we had tried to keep the C++ and Python similar, but it is evident that this is less useful than idiomatic Python that people will use in practice.

This means:

- Using `snake_case` instead of `camelCase` for variable names
- Not using type declarations, unless required
- Using the Pythonic functional interface to filters when possible
- Not hardcoding types or dimensions when possible