code: function crawlImage ($,result, img, callback) {
        var parentUrl = result.url;
  
        var link = $(img).attr('src');
        var alt = $(img).attr('alt');
        if (link) {
            var linkUri = URI.linkToURI(parentUrl, link);
            pm.crawlImage(parentUrl, linkUri, alt, function(){
              addLinkToQueue(result, parentUrl, linkUri, null, null, callback);
            });
        }
        else {
          callback();
        }
  }
docs: Extract info of an image tag & send the info to the plugins
  
  
  @param The HTML body containing the link (Cheerio wraper)
  @param The http response with the crawl options
  @param The image tag
  @param callback()