download image from url, save to '/dalle_images/' and return a full url of the image

function download_image($image_url) {
  $file_name = $image_url;
  $file_name = basename($file_name);
  $full_path = '/dalle_images/' . $file_name;
  $image_url = 'https://thecatapi.com/api/images/get?format=src&type=gif';
  file_put_contents($full_path, file_get_contents($image_url));
  return $full_path;
}