docs: function collectStats(callback) {
      var serviceStats = {};
      var services = loader.listServices();
      async.each(services, function(service, callback) {
          var mod = loader.get(service);
          if (mod.stats) { //does it have a stats function?
              invokeStatsOnMod(mod, function(err, data) {
                  serviceStats[service] = data;
                  return callback(err);
              });
          } else {
              return callback(); //nothing to do, no stats method exposed
          }
  
      }, function(err) {
          callback(err, serviceStats);
      });
  
  }