//var %x = $!eval(%x,2) | noop $eval(%x,2)
because it keeps evaluating %x
noop $eval(%x,2)
1:evaluates $!eval(%x,2) twice becoming
2:$eval(%x,2)
3:and the 2nd time it will evaluate the contents of %x twice again jumping to 1: again.
As you can see there's no end to it.
