<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def sanitized_uri(self):
 """ Return the database URI we're using in a format sensible for logging etc. :return: db_uri """

        if self._sanitized_uri is None:
            _parsed = copy.copy(self._parsed_uri)
            if 'username' in _parsed:
                _parsed['password'] = 'secret'
            _parsed['nodelist'] = [_parsed['nodelist'][0]]
            self._sanitized_uri = _format_mongodb_uri(_parsed)
        return self._sanitized_uri