Function parseRetryHeaders

packages/web-api/src/WebClient.ts:829–834

* Extract the amount of time (in seconds) the platform has recommended this client wait before sending another request * from a rate-limited HTTP response (statusCode = 429).

(response: AxiosResponse)

 * from a rate-limited HTTP response (statusCode = 429).
 */
function parseRetryHeaders(response: AxiosResponse): number | undefined {
  if (response.headers['retry-after'] !== undefined) {
    return parseInt((response.headers['retry-after'] as string), 10);
  }
  return undefined;
}