docs: def _get_connection(self):
          """ Returns connection to sqlite db.
  
          Returns:
              connection to the sqlite db who stores mpr data.
  
          """
          if getattr(self, '_connection', None):
              logger.debug('Connection to sqlite db already exists. Using existing one.')
          else:
              dsn = self._dsn
              if dsn == 'sqlite://':
                  dsn = ':memory:'
              else:
                  dsn = dsn.replace('sqlite:///', '')
  
              logger.debug(
                  'Creating new apsw connection.\n   dsn: {}, config_dsn: {}'
                  .format(dsn, self._dsn))
              self._connection = apsw.Connection(dsn)
  
          return self._connection