def METHOD_NAME(ytdl_instance, outtmpl):
    try:
        ytdl_instance._parse_outtmpl
    except AttributeError:
        try:
            ytdl_instance.outtmpl_dict["default"] = outtmpl
        except AttributeError:
            ytdl_instance.params["outtmpl"] = outtmpl
    else:
        ytdl_instance.params["outtmpl"] = {"default": outtmpl}