LoadHook
typealias LoadHook = (url: String, context: LoadHookContext, nextLoad: (url: String, context: LoadHookContext?) -> <Error class: unknown class><LoadFnOutput>) -> <Error class: unknown class><LoadFnOutput>(source)
The load hook provides a way to define a custom method of determining how a URL should be interpreted, retrieved, and parsed. It is also in charge of validating the import attributes.