First example doesn't work though:

    const greeting = pipe('hello')
       | upper
       | ex('!!!')

    await greeting.run() // → "HELLO!!!"

If you look at the tests file, it needs to be written like this to make it work:

    let greeting;
    (greeting = pipe('hello')) | upper | ex('!!!');
    await greeting.run();

Which is not anymore as ergonomic.