:returns: Return the default directory for a node type

def default_images_directory(type):
    """
    :returns: Return the default directory for a node type
    """
    server_config = Config.instance().get_section_config("Server")
    img_dir = os.path.expanduser(server_config.get("images_path", "~/GNS3/images"))
    if type == "qemu":
        return os.path.join(img_dir, "QEMU")
    elif type == "iou":
        return os.path.join(img_dir, "IOU")
    elif type == "dynamips":
        return os.path.join(img_dir, "IOS")
    else:
        raise NotImplementedError("%s node type is not supported", type)