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> get(key: K) -> Option<V>

This is also not clear whether the value is missing because it's not set or because it's set to nothing

You might want

> get(key: K) -> Option<Option<V>>

? But you can do that with nulls too, just a matter of having a box around the value

No, the type for `get` would only have a single layer of `Option`. But V is a type parameter, so you can instantiate it with another layer of Option. You don't need to (and shouldn't) modify the type signature of the `get` method. It's already generic.

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