function BlogService() {}

BlogService.prototype.getImageData = function(lineData) {
  var options = {
    'method': 'GET',
    'headers': {
      'Authorization': 'Bearer YOUR_BLOG_API_KEY'
    }
  };
  var response = UrlFetchApp.fetch('https://your-blog-api.com/image', options);
  return response.getContentText();
}