code: def watch(args):
      " Watch directory for changes and auto pack sources "
      assert op.isdir(args.source), "Watch mode allowed only for directories."
      print 'Zeta-library v. %s watch mode' % VERSION
      print '================================'
      print 'Ctrl+C for exit\n'
      observer = Observer()
      handler = ZetaTrick(args=args)
      observer.schedule(handler, args.source, recursive=True)
      observer.start()
      try:
          while True:
              time.sleep(1)
      except KeyboardInterrupt:
          observer.stop()
          print "\nWatch mode stoped."
      observer.join(f watch(args):
      " Watch directory for changes and auto pack sources "
      assert op.isdir(args.source), "Watch mode allowed only for directories."
      print 'Zeta-library v. %s watch mode' % VERSION
      print '================================'
      print 'Ctrl+C for exit\n'
      observer = Observer()
      handler = ZetaTrick(args=args)
      observer.schedule(handler, args.source, recursive=True)
      observer.start()
      try:
          while True:
              time.sleep(1)
      except KeyboardInterrupt:
          observer.stop()
          print "\nWatch mode stoped."
      observer.join()
docs: Watch directory for changes and auto pack sources