+sub add_provided_by {
+ my ($self, $provided_by) = @_;
+
+ $self->{provided_by} ||= [];
+ push @{$self->{provided_by}}, @$provided_by;
+}
+
+sub is_virtual {
+ my ($self) = @_;
+
+ return (exists($self->{provided_by}) && !exists($self->{versions}));
+}
+