Exponential back-off for S3 queries?

[ukstv]

First, thank you for the excellent library. Second, have you considered adding an exponential backoff for S3 requests?

According to the docs S3 has some flexible limits, but a client could once in a while get this "503 Slow Down" response. The docs propose using exponential backoff. I think, it is a responsibility of this library.

What do you think would be a good way to add an exponential backoff here?