Finds all objects associated with any of the keywords.

    Args:
      keywords: A collection of keywords that we are interested in.
      start_time: Only considers keywords added at or after this point in time.
      end_time: Only considers keywords at or before this point in time.
      last_seen_map: If present, is treated as a dict and populated to map pairs
        (keyword, name) to the timestamp of the latest connection found.
    Returns:
      A dict mapping each keyword to a set of relevant names.

def ReadPostingLists(self,
                       keywords,
                       start_time=FIRST_TIMESTAMP,
                       end_time=LAST_TIMESTAMP,
                       last_seen_map=None):
    """Finds all objects associated with any of the keywords.

    Args:
      keywords: A collection of keywords that we are interested in.
      start_time: Only considers keywords added at or after this point in time.
      end_time: Only considers keywords at or before this point in time.
      last_seen_map: If present, is treated as a dict and populated to map pairs
        (keyword, name) to the timestamp of the latest connection found.
    Returns:
      A dict mapping each keyword to a set of relevant names.

    """
    return data_store.DB.IndexReadPostingLists(
        self.urn, keywords, start_time, end_time, last_seen_map=last_seen_map)