While this instance lookup might seem trivial and obvious, it highlights a hidden superpower of the trait system, which is that it gives us dependency injection for free. Our Display implementation for Person is able to require an implementation of Display for Name inside the where clause, without explicitly declaring that dependency anywhere else. This means that when we define the Person struct, we don't have to declare up front that Name needs to implement Display. And similarly, the Display trait doesn't need to worry about how Person gets a Display instance for Name.
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Иллюстрация: Кирилл Брага / РИА Новости
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