ncodeproject.org/files/ENCFF563PAW/@@download/ENCFF563PAW.bigWig"}</pre>
    </li>
    <li>A promise
        <pre>url: Promise.resolve("https://www.encodeproject.org/files/ENCFF563PAW/@@download/ENCFF563PAW.bigWig")</pre>
    </li>
    <li>A function that returns a promise
        <pre>url: function () {return Promise.resolve("https://www.encodeproject.org/files/ENCFF563PAW/@@download/ENCFF563PAW.bigWig")}</pre>
    </li>
    <li>A function that returns a thenable
        <pre>url: function () {return {then