t1 = currentTimeMillis();
try {
p3.merge(pn, ncpn);
// Change the input proto-network descriptor to merged network
ProtoNetworkExternalizer pne = new BinaryProtoNetworkExternalizer();
final String artpath = artifactPath.getAbsolutePath();
final String s2path = asPath(artpath, STAGE2_OUTPUT);
createDirectoryArtifact(artifactPath, STAGE2_OUTPUT);
pne.writeProtoNetwork(pn, s2path);
// if debug, then save the text-based merged network
if (withDebug()) {
TextProtoNetworkExternalizer textExternalizer =
new TextProtoNetworkExternalizer();