code: def post_message(consumers, lti_key, url, body):
      
      content_type = 'application/xml'
      method = 'POST'
      (_, content) = _post_patched_request(
          consumers,
          lti_key,
          body,
          url,
          method,
          content_type,
      )
  
      is_success = b"<imsx_codeMajor>success</imsx_codeMajor>" in content
      log.debug("is success %s", is_success)
      return is_success
docs: Posts a signed message to LTI consumer
  
      :param consumers: consumers from config
      :param lti_key: key to find appropriate consumer
      :param url: post url
      :param body: xml body
      :return: success