This package implements the backoff strategy described in the AWS Architecture
Blog article "Exponential Backoff And Jitter". Essentially, the backoff has an
interval time.Duration; the nth call to backoff will return an a time.Duration
that is 2 n * interval. If jitter is enabled (which is the default behaviour),
the duration is a random value between 0 and 2 n * interval. The backoff is
configured with a maximum duration that will not be exceeded; e.g., by default,
the longest duration returned is backoff.DefaultMaxDuration.
