Instructor: 00:00 Import subscriber. Then this is a class which we can extend. I'll call this double subscriber. Extends subscriber. Then I'm simply going to implement an _next function, which takes a value and then with that value calls this destination, next. I'm going to pass in that value times two.
00:27 With this double subscriber, which is not being used yet, I'm going to subscribe to a new instance of the double subscriber and pass in our subscriber from above.
00:42 You can see up here that the values are now 2, 4, 6, 8, 10. The values coming into here, if I just log these out, are one, two, three, four, five. Then they get doubled and passed down to this subscriber.
00:56 This destination is simply this subscriber. This double subscriber is wrapping that subscriber and transforming that value before it passes it on.