def METHOD_NAME(overlay="ALL"):
    """
    Update the specified overlay. Use 'ALL' to synchronize all overlays.
    This is the default if no overlay is specified.
    overlay
        Name of the overlay to sync. (Defaults to 'ALL')
    CLI Example:
    .. code-block:: bash
        salt '*' layman.sync
    """
    cmd = "layman --quietness=0 --sync {}".format(overlay)
    return __salt__["cmd.retcode"](cmd, python_shell=False) == 0