code: def get_token(access_token=None, refresh_token=None):
      
      if access_token:
          t = Token.query.filter_by(access_token=access_token).first()
          if t and t.is_personal and t.user.active:
              t.expires = datetime.utcnow() + timedelta(
                  seconds=int(current_app.config.get(
                      'OAUTH2_PROVIDER_TOKEN_EXPIRES_IN'
                  ))
              )
      elif refresh_token:
          t = Token.query.join(Token.client).filter(
              Token.refresh_token == refresh_token,
              Token.is_personal == False,  # noqa
              Client.is_confidential == True,
          ).first()
      else:
          return None
      return t if t and t.user.active else None
docs: Load an access token.
  
      Add support for personal access tokens compared to flask-oauthlib.
      If the access token is ``None``, it looks for the refresh token.
  
      :param access_token: The access token. (Default: ``None``)
      :param refresh_token: The refresh token. (Default: ``None``)
      :returns: The token instance or ``None``.