func (pool *Pool) subworker(job *Job) {
	defer func() {
		if err := recover(); err != nil {
			log.Println("panic while running job:", err)
			job.Result = nil
			job.Err = fmt.Errorf(err.(string))
		}
	}()
	job.Result = job.F(job.Args...)
}
func (pool *Pool) subworker(job *Job) {
	defer func() {
		if err := recover(); err != nil {
			log.Println("panic while running job:", err)
			job.Result = nil
			job.Err = fmt.Errorf(err.(string))
		}
	}()
	job.Result = job.F(job.Args...)
}
// subworker catches any panic while running the job.