3 int total = 0;  variable
7     case 0: total += 1 + 0; return 1;  in inc()
8     case 1: total += 1 + 1; return 2;  in inc()
9     case 2: total += 1 + 2; return 3;  in inc()
10     case 3: total += 1 + 3; return 4;  in inc()
11     case 4: total += 1 + 4; return 5;  in inc()
12     case 5: total += 1 + 5; return 6;  in inc()
19     case 0: total += 2 + 0; return 1;  in inc_dup()
20     case 1: total += 2 + 1; return 2;  in inc_dup()
21     case 2: total += 2 + 2; return 3;  in inc_dup()
22     case 3: total += 2 + 3; return 4;  in inc_dup()
23     case 4: total += 2 + 4; return 5;  in inc_dup()
24     case 5: total += 2 + 5; return 6;  in inc_dup()