classify_response(status) mapping an HTTP status integer to 'success' (2xx), 'redirect' (3xx), 'client-error' (4xx), 'server-error' (5xx) or 'unknown' — integer division by 100 beats a lookup table of every code.classify_response(201)
'success'
201 Created is in the 2xx family.
classify_response(503)
'server-error'
5xx means the server failed.
status // 100 gives the family digit.
A dict maps 2/3/4/5 to the labels.