4. (10 points) Synchronization The test_and set() instruction and its usage are given in the code below. Explain in a few sentences how the test and set() instruction provides mutual exclusion for the critical section problem below boolean test and set (boolean *target) boolean rv - *target; *target true; return rv; do while (test and set (&lock)) ;/*do nothing/ /*critical section/ lock false; /* remainder section / while (true)