Your feedback and comments are welcome:)

First; you really need to separate the different types of collections (List, Set, Map) from their concrete implementations. When do you use a Set? A Map? A List? And secondly you need to take the step that when you know you need a list, which one do you pick and why?

Basically you just showed a bunch of code that does not explain anything about the "why". The official tutorials do a MUCH better job at that, so for now your tutorials don't add anything and just dilute the quality of available content.

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