text: // checks a single memory overflow.
  #include "rpi.h"
  #include "purify.h"
  
  void notmain(void) {
      trace("should detect use after free bug (store at offset 3)\n");
      purify_init();
  
      char *p = purify_alloc(4);
      purify_free(p); 
      p[3] = 1;
      panic("should have caught use-after-free before\n");
  }
  