code: def _add_finder(importer, finder):
    
  
    existing_finder = _get_finder(importer)
  
    if not existing_finder:
      pkg_resources.register_finder(importer, finder)
    else:
      pkg_resources.register_finder(importer, ChainedFinder.of(existing_finder, finder))
docs: Register a new pkg_resources path finder that does not replace the existing finder.