[@react.component]
let make = (~children) => {
  let (show, setShow) = React.useState(() => true);

  // Notice that instead of `useEffect`, we have `useEffect0`. See
  // reasonml.github.io/reason-react/docs/en/components#hooks for more info
  React.useEffect0(() => {
    let id =
      Js.Global.setInterval(
        () => setShow(previousShow => !previousShow),
        1000,
      );

    Some(() => Js.Global.clearInterval(id));
  });

  let style =
    if (show) {
      ReactDOM.Style.make(~opacity="1", ~transition="opacity 1s", ());
    } else {
      ReactDOM.Style.make(~opacity="0", ~transition="opacity 1s", ());
    };

  <div style> children </div>;
};