docs: public static boolean save(ZMsg msg, DataOutputStream file)
      {
          if (msg == null) {
              return false;
          }
  
          try {
              // Write number of frames
              file.writeInt(msg.size());
              if (msg.size() > 0) {
                  for (ZFrame f : msg) {
                      // Write byte size of frame
                      file.writeInt(f.size());
                      // Write frame byte data
                      file.write(f.getData());
                  }
              }
              return true;
          }
          catch (IOException e) {
              return false;
          }
      }