text: #include "types.h"
  #include "user.h"
  
  void hello(int);
  
  int main(int argc, char** argv) {
    signal(2,hello);
    while(1) {
      printf(1,"Hello, still looping!\n");
      sleep(100);
    }
  }
  
  void hello(int signum) {
    printf(1,"Nuh-uh, I'm a non-preemptable hello loop!\n");
  }
  
  