16                      const uint8_t* val, 
size_t size_of_val) {
 
   20  CHECK(size_of_formatted >= (size_of_val * 2));
 
   22  for (
size_t index = 0; index < size_of_val; index++) {
 
   23    size_t dest_index = index << 1;
 
   24    snprintf(&
formatted[dest_index], size_of_formatted - dest_index, 
"%02x",