code: func (a *Core) postAsGet(uri string, response interface{}) (*http.Response, error) {
  	return a.retrievablePost(uri, []byte{}, response)
  }
docs: // postAsGet performs an HTTP POST ("POST-as-GET") request.
  // https://tools.ietf.org/html/draft-ietf-acme-acme-16#section-6.3