function _prompt_single_image(image_seq_len, fake_token_around_image, image_token, global_img_token) {
    return (
        `${fake_token_around_image}` +
        `${global_img_token}` +
        image_token.repeat(image_seq_len) +
        `${fake_token_around_image}`
    );
}
Prompt with expanded image tokens for a single image.
@private