use CGI;
my $query = new CGI;

my $slice = $query->param('slice');
my $next_qs = build_qs($query, slice => $slice + 1);

sub build_qs {
	my ($query, %new_param) = @_;
	my %parameters = map { $_ => $query->param($_) } $query->param;
	$parameters{$_} = $new_param{$_} for keys %new_param;
	return join '&', 
		   map { "$_=$parameters{$_}" } 
		   keys %parameters;
}