code: func (r *Runner) Close() {
  	r.init()
  
  	close(r.workC)
  	<-r.dispatchFinishedC
  }
docs: // Close will instruct the Runner to not accept any more jobs and block until
  // all current work is finished.
  //
  // Close may only be called once; additional calls will panic.
  //
  // The Runner's dispatch methods will panic if new work is dispatched after
  // Close has been called.