code: def get_authorize_callback(endpoint, provider_id):
      
      endpoint_prefix = config_value('BLUEPRINT_NAME')
      url = url_for(endpoint_prefix + '.' + endpoint, provider_id=provider_id)
      return request.url_root[:-1] + url
docs: Get a qualified URL for the provider to return to upon authorization
  
      param: endpoint: Absolute path to append to the application's host