And it's called the chain rule. And when you're first exposed to it, it can seem a little daunting and a little bit convoluted. But as you see more and more examples, it'll start to make sense. And hopefully, it'll even start to seem a little bit simple and intuitive over time. So let's say that I had a function. Let's say I have a function h of x. And it is equal to, just for example, let's say it's equal to sine of x.