This comes from archive/ReactFake.js
function createElement(tag, attrs, children) {        // Note arguments is set to tag, attrs, child1, child2 etc
    /* Replaces React's createElement - has a number of application specific special cases
        <img src=ArchiveFile(...)> replaced by <div><img x-=u>

     */

    /* First we handle cases where we dont actually build the tag requested */

    const kids = Array.prototype.slice.call(arguments).slice(2);

    /* Special cases go here - see examples in archive/ReactFake.js---- */
    return buildoutElement(document.createElement(tag), tag, attrs, kids);
}