..like mentioned above: the syntax just doesnt allows to handle switches like that..
..if you want to set the -u4timer each time you increase the var just do:
$iif(!%a,inc -u4 %a)
..else, if you want the var to be set for 4 seconds and only beeing increased during the 4 seconds:
$iif(!%a,set -u4 %a,inc %a)
.
