code: function fetchConfiguration(environment, applicationId, callback) {
      if(!applicationId) {
          logger.error("No application ID specified");
          return;
      }
  
      var deviceDetails = deviceDetector.getDeviceDetails();
  
      var pathname = environment.getPathname();
      var formFactor = deviceDetails.formFactor;
  
      var requestUrl = "";
      var queryParams = {};
  
      if (appSettings.overrides && appSettings.overrides.configFileLocation) {
        requestUrl = appSettings.overrides.configFileLocation;
      }else{
        requestUrl = appSettings.configurationsApiUrl;
        queryParams = {
            path: pathname,
            device: formFactor,
            "application_id":applicationId
        };
      }
  
      ajax.get({
          url: requestUrl,
          query: queryParams,
          success: function (data) {
              if (appSettings.overrides && appSettings.overrides.configFileLocation){
                callback(null, data.adUnits);
              }else{
                callback(null, data);
              }
          },
          error: function (err) {
              callback(err, null);
          }
      });
  }
docs: Fetch the ad configurations to load on the current page from the server
  @param environment - The environment specific implementations
  @param applicationId - The applicationId to fetch ad configurations for
  @param callback - The callback to execute when the configurations are retrieved