Factory Method

Let a method decide which object to build

Factory Method puts object creation behind a function so callers ask for what they want, not how it's made. When a booking update needs to go out, you don't want if channel == ... scattered everywhere — you want one notifier_for(channel) that returns the right notifier.

In Python this is just a function that returns an object. No abstract creator class required — a dict or an if/elif does the job.