text: #include "lib/common.h"
  
  int another_shared = 0;
  
  void * thread_run(void *arg) {
      int *calculator = (int *) arg;
      printf("hello, world, tid == %d \n", pthread_self());
      for (int i = 0; i < 1000; i++) {
          *calculator += 1;
          another_shared += 1;
      }
  }
  
  int main(int c, char **v) {
      int calculator;
  
      pthread_t tid1;
      pthread_t tid2;
  
      pthread_create(&tid1, NULL, thread_run, &calculator);
      pthread_create(&tid2, NULL, thread_run, &calculator);
  
      pthread_join(tid1, NULL);
      pthread_join(tid2, NULL);
  
      printf("calculator is %d \n", calculator);
      printf("another_shared is %d \n", another_shared);
  }