Instruction: Describe the keyof operator and provide an example of its use.
Context: This question tests the candidate's understanding of the keyof operator and its role in TypeScript's type system.
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The keyof operator takes an object type and produces a union type of its keys. Essentially, it extracts the keys of an object type and creates a type that represents all possible keys of that object as string literals. This is particularly useful in scenarios where you need to ensure that a function or a method accepts only the keys that exist on a specific object, enhancing type safety and reducing runtime errors.
For example, let's consider an interface User that represents a user in a system:...