$self->_set->{$self->_spec_to_key($spec)};
}
+sub remove {
+ my ($self, $spec) = @_;
+ delete $self->_set->{$self->_spec_to_key($spec)};
+}
+
+sub flatten {
+ my ($self) = @_;
+ my $set = $self->_set;
+ map $set->{$_}, sort keys %$set;
+}
+
sub _spec_to_object {
my ($self, $spec) = @_;
if (blessed($spec) && $spec->isa($self->_set_of_class)) {