code: def _get_oauth_token(self):
          
          url = urljoin(self.api_url, '/oauth2/token')
  
          oauth = OAuth2Session(
              client_id=self._client_id,
              redirect_uri=config.REDIRECT_URI,
          )
  
          token = oauth.fetch_token(
              token_url=url,
              code=self._auth_code,
              client_secret=self._client_secret,
          )
  
          return token
docs: Get Monzo access token via OAuth2 `authorization code` grant type.
  
          Official docs:
              https://monzo.com/docs/#acquire-an-access-token
  
          :returns: OAuth 2 access token
          :rtype: dict