docs: def _index_document(self, document, force=False):
          """ Adds parition document to the index. """
          from ambry.util import int_maybe
          time_coverage = document.pop('time_coverage', [])
          from_year = None
          to_year = None
          if time_coverage:
              from_year = int_maybe(time_coverage[0])
              to_year = int_maybe(time_coverage[-1])
  
          query = text("""
              INSERT INTO partition_index(vid, dataset_vid, title, keywords, doc, from_year, to_year)
              VALUES(:vid, :dataset_vid, :title, :keywords, :doc, :from_year, :to_year); """)
          self.backend.library.database.connection.execute(
              query, from_year=from_year, to_year=to_year, **document)