code: private boolean stage7(final ProtoNetwork pn, final Document doc) {
          beginStage(PHASE1_STAGE7_HDR, "7", NUM_PHASES);
          final StringBuilder bldr = new StringBuilder();
  
          bldr.append("Saving proto-network for ");
          bldr.append(doc.getName());
          stageOutput(bldr.toString());
  
          long t1 = currentTimeMillis();
          String dir = artifactPath.getAbsolutePath();
          final String path = asPath(dir, nextUniqueFolderName());
          File pnpathname = new File(path);
  
          boolean success = true;
          try {
              p1.stage7Saving(pn, pnpathname);
  
              if (withDebug()) {
                  TextProtoNetworkExternalizer textExternalizer =
                          new TextProtoNetworkExternalizer();
                  textExternalizer.writeProtoNetwork(pn,
                          pnpathname.getAbsolutePath());
              }
          } catch (ProtoNetworkError e) {
              success = false;
              error("failed to save proto-network");
              e.printStackTrace();
          }
          long t2 = currentTimeMillis();
  
          bldr.setLength(0);
          markTime(bldr, t1, t2);
          markEndStage(bldr);
          stageOutput(bldr.toString());
  
          return success;
      }
docs: Stage seven saving of proto-network.
  
  @param pn Proto-network
  @param doc {@link Document}, the document
  @return boolean true if success, false otherwise