+}
+
+sub lookup_newsgroup {
+ my ($self, $ng) = @_;
+ $ng = lc($ng);
+ my $rv = $self->{-by_newsgroup}->{$ng};
+ return $rv if $rv;
+
+ foreach my $k (keys %$self) {
+ $k =~ /\A(publicinbox\.[\w-]+)\.newsgroup\z/ or next;
+ my $v = $self->{$k};
+ my $pfx = $1;
+ if ($v eq $ng) {
+ $rv = _fill($self, $pfx);
+ return $rv;
+ }
+ }
+ undef;