'Refresh access token.'

def refresh_access_token(self, refresh_token, redirect_uri=None):

    redirect = (redirect_uri or self._redirect_uri)
    resp_text = _http('POST', 'https://graph.qq.com/oauth2.0/token', refresh_token=refresh_token, client_id=self._client_id, client_secret=self._client_secret, redirect_uri=redirect, grant_type='refresh_token')
    return self._parse_access_token(resp_text)
