code: def get_page_access_token(self, app_id, app_secret, user_token):
          
          url_extend = (
              self._url_base + '/oauth/access_token?grant_type=fb_exchange_token&'
                               'client_id=%(app_id)s&client_secret=%(app_secret)s&fb_exchange_token=%(user_token)s')
  
          response = self.lib.get(url_extend % {'app_id': app_id, 'app_secret': app_secret, 'user_token': user_token})
  
          user_token_long_lived = response.text.split('=')[-1]
  
          response = self.lib.get(self._url_versioned + '/me/accounts?access_token=%s' % user_token_long_lived)
          json = response.json()
  
          tokens = {item['name']: item['access_token'] for item in json['data'] if item.get('access_token')}
  
          return tokens
docs: Returns a dictionary of never expired page token indexed by page names.
  
          :param str app_id: Application ID
          :param str app_secret: Application secret
          :param str user_token: User short-lived token
          :rtype: dict