[Challenge] Design patterns

Question

Show your implementation of a design pattern of your choice in the language of your choice. Add comments to explain your code a bit.
This is meant as a showcase for users with basic programming skills to show them which design patterns can be used in different scenarios.

I'll start with an observer pattern implemented in a scenario where a space fleet (observers) gets updates about the damage of their mothership.
https://code.sololearn.com/c8UbMs6vj3a9/?ref=app

Answer 1

here is mine

https://code.sololearn.com/cxB4tyBxjVCD/?ref=app