How to use the zalgo-promise.ZalgoPromise.resolve function in zalgo-promise

            once: () => cancelablePromise(ZalgoPromise.resolve()),
            send: () => cancelablePromise(ZalgoPromise.resolve())

signInWithCustomToken: () => {
                    return ZalgoPromise.resolve();
                }
            };

function runScripts(el) {
    let promise = ZalgoPromise.resolve();

    Array.prototype.slice.call(el.querySelectorAll('script')).forEach(script => {
        promise = promise.then(() => {
            return new ZalgoPromise((resolve, reject) => {
                let parentNode = script.parentNode;

                if (!parentNode) {
                    return;
                }

                let newScript = document.createElement('script');

                newScript.onload = resolve;
                newScript.onerror = reject;

                parentNode.replaceChild(newScript, script);