code: function _updateSingleton() {
      if (!options.singletons) {
        return;
      }
      if (process.rebusinstances[folder]) {
        // Somebody added instance already.
        return;
      }
      // Save this instance to return the same for the same folder.
      process.rebusinstances[folder] = instance;
    }
docs: Store the instance of rebus per process to be reused if requried again.