def METHOD_NAME(path: str, ds: datastore) -> et.ElementTree:
    """Convert old XML into the new format."""
    old_tree = xml.open_file(path, 'project')
    new_root = et.Element('gtgData')
    # Bump this on each new GTG release, no matter what:
    new_root.set('appVersion', '0.6')
    # Bump this when there are known file format changes:
    new_root.set('xmlVersion', '2')
    taglist, searches = convert_tags(old_tree)
    new_root.append(taglist)
    new_root.append(searches)
    tasklist = et.SubElement(new_root, 'tasklist')
    for task in old_tree.iter('task'):
        # Keep a map of old style IDs to UUIDs for later
        tid = task.attrib['id']
        try:
            new_tid = task.attrib['uuid']
        except KeyError:
            new_tid = str(uuid4())
        tid_cache[tid] = new_tid
    for task in old_tree.iter('task'):
        new_task = convert_task(task, ds)
        if new_task is not None:
            tasklist.append(new_task)
    return et.ElementTree(new_root)