void
onData(Face& face,
       const Interest& interest, Data& data)
{
  std::cout << "I: " << interest.toUri() << std::endl;
  std::cout << "D: " << data.getName().toUri() << std::endl;
}
 void
 onInterestLeaves(Consumer& c, Interest& interest)
 {
   std::cout << "Leaving: " << interest.toUri() << std::endl;
 }
 void
 processLeavingInterest(Consumer& c, Interest& interest)
 {
   std::cout << "LEAVES  " << interest.toUri() << std::endl;
 }  
 void
 onP2(Producer& p, const Interest& interest)
 {
   std::cout << "Producer 2 got " << interest.toUri() << std::endl;
 }