Implementation of NB can be much more interesting than that:

- try different models for the likelihood (the author mentioned Gaussian, Bernoulli, and Multinomial which are part of scikit but didn't bother to implement them)

- understand how the "naive" assumption makes implementation easier but less expressive (author mentions it in words but pictures are critical here, e.g. the Gaussian case)

- using log probabilities for numerical stability

- reframing the model as a linear model