What is the reason for considering IReference in WinRT an interface?

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IReference in WinRT is considered an interface because it defines a contract between a consumer and a provider. The consumer requires a way to access a value that may or may not be present, and the provider gives a means of accessing that value if it's there. This contract, which specifies the methods and properties that must be implemented by the provider, ensures that both parties understand how to interact with each other correctly. Hence, IReference is an interface in WinRT.