I think this feature is useful and would help alot. Which we can handle the result and get out from the -k property. The examples tells alot..

/filter -gff [+f flag] file nul .+
The flag feature is optional.

on *:filter:{
if $fflag == test {
if $fevent == filter {
echo -a $fresult which is it the $1 in the -k property
}
elseif $fevent == filtered {
echo -a finished filtering - $filtered
}
}
}