code: def _reference_info(references):
      
      document_paths = []
      reference_map = {}
      for reference in references:
          doc_path = reference._document_path
          document_paths.append(doc_path)
          reference_map[doc_path] = reference
  
      return document_paths, reference_map
docs: Get information about document references.
  
      Helper for :meth:`~.firestore_v1beta1.client.Client.get_all`.
  
      Args:
          references (List[.DocumentReference, ...]): Iterable of document
              references.
  
      Returns:
          Tuple[List[str, ...], Dict[str, .DocumentReference]]: A two-tuple of
  
          * fully-qualified documents paths for each reference in ``references``
          * a mapping from the paths to the original reference. (If multiple
            ``references`` contains multiple references to the same document,
            that key will be overwritten in the result.)