code: function applyExternalEffect(effect) {
          var changed = false;
          if (effect.sent.length > 0) {
              options.enqueue(events, effect.sent);
              changed = true;
          }
          if (effect.created.length > 0) {
              changed = true;
          }
          if (changed) {
              initEffect(effect);
          }
      }
docs: /*
  Conditionally apply accumulated external effects.