simple checkbox in react using hooks / useState

One of those, oh right duh --
const [thereminMode, setThereminMode] = React.useState(true);

and then the checkbox:
<input checked={thereminMode} type="checkbox" onChange={() => setThereminMode(!thereminMode)} />

It took me a second to realize, we don't have to read anything from the event or the checkbox itself, the verb "change" is enough to do the toggle ourself...