void
EdgeStrategy::toPreserve( ndn::Data& data,
                          const ndn::Interest& interest )
{
    if( data.getContentType() == ndn::tlv::ContentType_Nack )
    {
        data.setContent( ndn::Block() );
        data.wireEncode();
    }
}
void
EdgeStrategy::toNack( ndn::Data& data, const ndn::Interest& interest )
{
    // ensure that denied data doesn't leave the network
    data.setContent( ndn::Block() );
    data.wireEncode();
    
    // do whatever a normal router would do
    RouterStrategy::toNack( data, interest );
}