Returning a promise when using async/await in Firebase Cloud Functions

So I've happily been using async/await since node 8 is supported on Firebase Cloud Functions. I am struggling with 1 thing though. When using callable functions, it is told that you have to return a promise in the function, otherwise it won't work correctly. When using raw promises, its clear to me how to use it:

exports.createBankAccount = functions.region('europe-west1').https.onCall((data, context) => {
    return promiseMethod().then((result) => {
        return nextPromise(result);
    }).then((result) => {
        return result;
    }).catch((err) => {
        // handle err
    })
});

But now, with async await, I'm not sure how to return this "chain of promises":

exports.createBankAccount = functions.region('europe-west1').https.onCall(async (data, context) => {
    const res1 = await promiseMethod();
    const res2 = await nextPromise(res1);
    return res2;
    // ??? Where to return the promise?
});

Does somebody know?

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