This is for people who write Python every week and now need it to handle bigger data, more work at the same time, and other people installing it. You will build real decorators, process data one piece at a time, catch type errors before they run, choose between threads, processes and asyncio, then package and profile your code. Most of this is not needed for small scripts. When it is needed, not knowing it gets expensive.
This is for people who already write Node and browser JavaScript with modules, async/await and tests, and now need code that keeps working under real load. You will learn how closures and this really behave, how the event loop orders your code, how to run, limit and cancel async work, how to process data that doesn't fit in memory, how to catch type bugs without switching to TypeScript, and how to ship a package and find slow code and memory leaks. If you skip this level, your code passes every test and still falls over the first week it runs in production.