code: function Stopping(worker, startedAt) {
      var spec = worker.spec;
      this.worker = worker;
      this.nextState = null;
      this.isDebugging = false;
      this.startedAt = startedAt;
      this.stopRequestedAt = Date.now();
      this.forceStopHandle = null;
      this.forceStopAt = null;
      this.forcedStop = false;
      this.forceStopDelay = spec.forceStopDelay;
  
      // Schedule a forceful shutdown if graceful shutdown does not complete in a
      // timely fashion.
      if (this.forceStopDelay < Infinity) {
          this.forceStopAt = Date.now() + this.forceStopDelay;
          this.forceStopHandle = setTimeout(
              this.handleForceStopTimeout.bind(this),
              this.forceStopDelay
          );
      }
  }
docs: ### Stopping state