What's the use case for __new__ method to return an object of a different type than its first arg?

The documentation implies that it's ok for __new__(cls, ...) to return an object of a type different than cls. It says in that case __init__() won't be called. It's not stated explicitly, but common sense or a simple test confirms that the resulting the object won't have type cls.

Why is this seemingly strange behavior allowed? What's the use case? It's clearly intentional.

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