So far, you've learned about Observables, Flowables, Subjects, processors, operators, combining producers, testing, and many more things. We have gained most of the necessary knowledge to start coding our applications. The only remaining topic to look at is resource management—the technique of creating, accessing, and cleaning up resources. Also if you're one of the developers who is hungry for a challenge, then you'll always look for ways to customize everything. So far in this book, we've seen how to use operators in their prescribed way. We did nothing innovative and didn't try to customize the operators. So, this chapter is dedicated to resource management and extending RxKotlin through custom operators.

The following list contains the topics we will cover in this chapter:

• Resource management with the using method
• Creating custom operators with the lift operator
• Creating custom transformers (transforming operators) with the compose operator

So, first things first, let's get started with resource management.