npm install preact-transitioningimport { useState } from 'preact/hooks';import { FadeTransition } from 'preact-transitioning'; export function Disclosure() { const [open, setOpen] = useState(false); return ( <section> <button onClick={() => setOpen(value => !value)}>Toggle</button> <FadeTransition in={open} unmountOnExit> <p>Animated content</p> </FadeTransition> </section> );}