<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def reload(self):
 """Reload server configuration."""

        status = self.get_status()
        if status != 'running':
            raise ClusterError('cannot reload: cluster is not running')

        process = subprocess.run(
            [self._pg_ctl, 'reload', '-D', self._data_dir],
            stdout=subprocess.PIPE, stderr=subprocess.PIPE)

        stderr = process.stderr

        if process.returncode != 0:
            raise ClusterError(
                'pg_ctl stop exited with status {:d}: {}'.format(
                    process.returncode, stderr.decode()))