code: def _init_index(root_dir, schema, index_name):
      
  
      index_dir = os.path.join(root_dir, index_name)
      try:
          if not os.path.exists(index_dir):
              os.makedirs(index_dir)
              return create_in(index_dir, schema), index_dir
          else:
              return open_dir(index_dir), index_dir
      except Exception as e:
          logger.error("Init error: failed to open search index at: '{}': {} ".format(index_dir, e))
          raise
docs: Creates new index or opens existing.
  
      Args:
          root_dir (str): root dir where to find or create index.
          schema (whoosh.fields.Schema): schema of the index to create or open.
          index_name (str): name of the index.
  
      Returns:
          tuple ((whoosh.index.FileIndex, str)): first element is index, second is index directory.