Returns default microseconds buckets for measuring http requests duration:

iex(6)> Prometheus.Contrib.HTTP.microseconds_duration_buckets
[10, 25, 50, 100, 250, 500, 1000, 2500, 5000, 10000, 25000, 50000,
 100000, 250000, 500000, 1000000, 2500000, 5000000, 10000000]

Returns class of the http status code:

iex(7)> Prometheus.Contrib.HTTP.status_class(202)
'success'

Raises Prometheus.InvalidValueError exception if code is not a positive integer.