code: function crawl(options, callback) {
  
            // Case of retries
            if (options.currentRetries > 0) {
              log.error({"url" : options.url, "step" : "queue-resquester.crawl", "message" : "Retry the request with a delay : " + options.retryTimeout});
              setTimeout(function() {
                execHttp(options, callback);
              }, options.retryTimeout);
              return;
            }
  
            // Case of a ratelimit forcing
            if (options.rateLimits !== 0) {
  
                log.error({"url" : options.url, "step" : "queue-resquester.crawl", "message" : "Request with option on ratelimit = " + options.rateLimits});
                setTimeout(function() {
                  execHttp(options, callback);
                }, options.rateLimits);
  
            }
            // The usual case without delay
            else {
              execHttp(options, callback);
            }
  
  
    }
docs: Crawl one url with optionnaly a delay (rate limit)
  
  
  @param the crawl options
  @param the callback used to inform the queue that request is finished