code: def authorized(self):
          
          if self.redirect_url:
              next_url = self.redirect_url
          elif self.redirect_to:
              next_url = url_for(self.redirect_to)
          else:
              next_url = "/"
  
          try:
              self.session.parse_authorization_response(request.url)
          except TokenMissing as err:
              message = err.args[0]
              response = getattr(err, "response", None)
              log.warning("OAuth 1 access token error: %s", message)
              oauth_error.send(self, message=message, response=response)
              return redirect(next_url)
  
          try:
              token = self.session.fetch_access_token(
                  self.access_token_url, should_load_token=False
              )
          except ValueError as err:
              # can't proceed with OAuth, have to just redirect to next_url
              message = err.args[0]
              response = getattr(err, "response", None)
              log.warning("OAuth 1 access token error: %s", message)
              oauth_error.send(self, message=message, response=response)
              return redirect(next_url)
  
          results = oauth_authorized.send(self, token=token) or []
          set_token = True
          for func, ret in results:
              if isinstance(ret, (Response, current_app.response_class)):
                  return ret
              if ret == False:
                  set_token = False
  
          if set_token:
              self.token = token
          return redirect(next_url)
docs: This is the route/function that the user will be redirected to by
          the provider (e.g. Twitter) after the user has logged into the
          provider's website and authorized your app to access their account.