If you go over these limits when using our HTTP based APIs, including Incoming Webhooks,
Slack will start returning a HTTP 429 Too Many Requests error, a JSON object containing the
number of calls you have been making, and a Retry-After header containing the number of seconds
until you can retry.
Read the response header and if the Retry-After header has been set, parse and set it on the exception instance being raised.
According to https://api.slack.com/docs/rate-limits
Read the response header and if the
Retry-After
header has been set, parse and set it on the exception instance being raised.