rem: T = (struct cell*)-1;
add: T = T_UNDEFINED;
context: int tm_startup(){   /* building the hash table*/   hash_table = init_hash_table();   if (!hash_table)      return -1;   /* installing handlers for timers */   hash_table->timers[RETRASMISSIONS_LIST].timeout_handler = retransmission_handler;   hash_table->timers[FR_TIMER_LIST].timeout_handler              = final_response_handler;   hash_table->timers[WT_TIMER_LIST].timeout_handler             = wait_handler;   hash_table->timers[DELETE_LIST].timeout_handler                 = delete_handler;   /*first msg id*/   global_msg_id = 0;   T = (struct cell*)-1;   return 0;}