docs: public int getIndex(TimelineEvent event) {
          int index = -1;
  
          if (event != null) {
              for (int i = 0; i < events.size(); i++) {
                  if (events.get(i).equals(event)) {
                      index = i;
  
                      break;
                  }
              }
          }
  
          return index;
      }