Code guidelines

Use Kotlin.
Keep it simple!
Keep functions and classes reasonably short.
Minimize side effects.
Avoid force unwrap (!!) and lateinit. If needed, use ?: throw Exception("Meaningful message").
Use extensions.
- If they are shared, put them in a file <ClassName>Extensions (e.g. TextFieldExtensions.kt)
- If they are specific to a class/file, make them private.
Use idiomatic Kotlin (let, apply, also, etc.). But keep readability in mind! Often a simple if != null is better.
Prefer composition over inheritance.
Prefer immutability.
Prefer explicit type declarations for instance variables.
Use readable names.
If something is difficult to understand, add some documentation.
Use Rx in services / repos / business logic / view models and live data only to interface with the UI.
Use View binding.
Don't use ViewPager. User RecyclerView with SnapHelper or ViewPager2
Use static imports where possible (e.g. enums, string or drawable resources). This improves readability. It makes writing / copy pasting a bit annoying but reading is more frequent. Place cursor over code and press ALT+ENTER. AS will offer the import.
Use auto format.
Use sealed classes (for example to model different cell types in a RecyclerView).

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