code: def save_ipyvolumejs(
      target="", devmode=False, version=ipyvolume._version.__version_js__, version3js=__version_threejs__
  ):
      
      url = "https://unpkg.com/ipyvolume@{version}/dist/index.js".format(version=version)
      pyv_filename = 'ipyvolume_v{version}.js'.format(version=version)
      pyv_filepath = os.path.join(target, pyv_filename)
  
      devfile = os.path.join(os.path.abspath(ipyvolume.__path__[0]), "..", "js", "dist", "index.js")
      if devmode:
          if not os.path.exists(devfile):
              raise IOError('devmode=True but cannot find : {}'.format(devfile))
          if target and not os.path.exists(target):
              os.makedirs(target)
          shutil.copy(devfile, pyv_filepath)
      else:
          download_to_file(url, pyv_filepath)
  
      # TODO: currently not in use, think about this if we want to have this external for embedding,
      # see also https://github.com/jovyan/pythreejs/issues/109
      # three_filename = 'three_v{version}.js'.format(version=__version_threejs__)
      # three_filepath = os.path.join(target, three_filename)
      # threejs = os.path.join(os.path.abspath(ipyvolume.__path__[0]), "static", "three.js")
      # shutil.copy(threejs, three_filepath)
  
      return pyv_filename
docs: Output the ipyvolume javascript to a local file.
  
      :type target: str
      :param bool devmode: if True get index.js from js/dist directory
      :param str version: version number of ipyvolume
      :param str version3js: version number of threejs