docs: def sheets_service(self):
          """ A SpreadsheetsService singleton, used to perform
          operations on the actual spreadsheet. """
          if not hasattr(self, '_sheets_service'):
              service = SpreadsheetsService()
              service.email = self.google_user
              service.password = self.google_password
              service.source = SOURCE_NAME
              service.ProgrammaticLogin()
              self._sheets_service = service
          return self._sheets_service