Thus begins the definition of an extension on Bundle:

extension Bundle { func decode(_ file: String) -> [String: Astronaut] { guard let url = self.url(forResource: file, withExtension: nil) else { fatalError("Failed to locate (file) in bundle.") }

My only question is, what exactly is the "self" on line 3 doing for us? Usually I think of "self" as necessary to clear up confusion about which variable we're referring to (within the closure or outside the closure), but I don't see how there are two versions of anything here.

Thanks!