def METHOD_NAME(overlay):
    """
    Add the given overlay from the cached remote list to your locally
    installed overlays. Specify 'ALL' to add all overlays from the
    remote list.
    Return a list of the new overlay(s) added:
    CLI Example:
    .. code-block:: bash
        salt '*' layman.add <overlay name>
    """
    ret = list()
    old_overlays = list_local()
    cmd = "layman --quietness=0 --add {}".format(overlay)
    add_attempt = __salt__["cmd.run_all"](cmd, python_shell=False, stdin="y")
    if add_attempt["retcode"] != 0:
        raise salt.exceptions.CommandExecutionError(add_attempt["stdout"])
    new_overlays = list_local()
    # If we did not have any overlays before and we successfully added
    # a new one. We need to ensure the make.conf is sourcing layman's
    # make.conf so emerge can see the overlays
    if not old_overlays and new_overlays:
        srcline = "source /var/lib/layman/make.conf"
        makeconf = _get_makeconf()
        if not __salt__["file.contains"](makeconf, "layman"):
            __salt__["file.append"](makeconf, srcline)
    ret = [overlay for overlay in new_overlays if overlay not in old_overlays]
    return ret