// allocated pointers: empty
1: A = malloc();     // I allocate memory at address A and add that address to my list of allocated pointers
// allocated pointers: A
2: free(A);          // I find and remove A from my list of allocated pointers
// allocated pointers: empty
3: B = malloc();     // I allocate memory at address A and add that address to my list of allocated pointers
// allocated pointers: B
4: free(B);          // I find and remove B from my list of allocated pointers
// allocated pointers: empty