Forums Scripts & Popups ban list update

$ifban(): returns $true if banmask exist in ban list of the channel but doesn't work if I didn't retrieve ban list of the channel. now I wanna know that how do I update ban list of a channel by not using channel properties dialog?
usage: $ifban(<channel>,<banmask>)
alias ifban {
var %i = 1
while $ibl($1,%i) {
if ($ifmatch == $2) return $true
inc %i
}
}