32kk5 >:#._a,                          v
v"Correct output is:"a"5 5 5 5 5 5 5 5"<
>:#,_a,@

This tests k on k...
Output should be:
5 5 5 5 5 5 5 5
Correct output is:
5 5 5 5 5 5 5 5

Here is how the stack should look after the different steps, spaces for clarity:
First iteration of inner k:             555
Next itereation where inner k pops a 5: 55
Now it pushed five 5s:                  55 55555
Finally the code resumes at the 5:      55 55555 5