With Rails Aws Gem version 2, how do you configure it to use your access keys?

According to this blog post, the new version of the Aws gem switches the namespace from AWS to Aws. But what am I supposed to use instead of

Aws.config({
  access_key_id: "something",
  secret_access_key: "something"
})

It's explained here but doesn't say what the alternative is: http://ift.tt/1JHErKo

Instead, I get an error:

Uncaught exception: wrong number of arguments (1 for 0)