Put this in your variables tab and hit the ok button:

%a %b

%b %c

%c %d

%d %e

%e 5

Then type:

//echo -a $eval(%a,0) ~ $eval(%a,1) ~ $eval(%a,2) ~ $eval(%a,3) ~ $eval(%a,4) ~ $eval(%a,5)

The output is:

%a ~ %b ~ %c ~ %d ~ %e ~ 5

$eval(%a,0) evaluates %a 0 times, so it stays as "%a", without being interpreted as a variable at all.

$eval(%a,1) evaluates it once, so it will return %b, without evaluating %b

$eval(%a,2) will first evaluate %a to %b, and then %b to %c, because it's evaluating twice.

$eval(%a,3) will do %a to %b, then %b to %c, then %c to %d

$eval(%a,4) will do %a to %b, then %b to %c, then %c to %d, then %d to %e

$eval(%a,5) will do %a to %b, then %b to %c, then %c to %d, then %d to %e, then %e to 5.