text: #ifndef TASK_H
  #define TASK_H
  
  struct task {
      int fd;
      struct task *next;
  };
  
  struct task_set {
      int task_set_len;
      struct task *front, *rear;
  };
  
  struct task *task_create(int fd);
  struct task_set *task_set_init();
  void task_add(struct task_set *ts, int fd);
  int task_get(struct task_set *ts);
  
  #endif
  