udat before:
[- @ks = grep (!/^_/, sort (keys %udat)) ; $num = keys (%udat) - $#ks - 1 ; -]
[+ $ks[$row] +]
[+ 0+$udat{$ks[$row] || ''} +]
[+ $num > 0?"ok (num=$num)":"Not a session hash (num=$num)" +]
$mdat{cnt} = -[+ 0+$mdat{cnt} +]-
$udat{cnt} = -[+ $udat{cnt} +]-
[- $_[0] -> DeleteSession (1) ; -]