docs: function FlowEvent(category, id, title, colorId, start, args, opt_duration) {
      tr.model.TimedEvent.call(this, start);
  
      this.category = category || '';
      this.title = title;
      this.colorId = colorId;
      this.start = start;
      this.args = args;
  
      this.id = id;
  
      this.startSlice = undefined;
      this.endSlice = undefined;
  
      this.startStackFrame = undefined;
      this.endStackFrame = undefined;
  
      if (opt_duration !== undefined)
        this.duration = opt_duration;
    }