# File lib/aws/dynamo_db/client.rb, line 87
      def sleep_durations response

        retry_count =
          if expired_credentials?(response)
            config.max_retries == 0 ? 0 : 1
          else
            config.max_retries { 10 }
          end

        # given a retry_count of 10, the sleep durations will look like:
        # 0, 50, 100, 200, 400, 800, 1600, 3200, 6400, 12800 (milliseconds)
        (0...retry_count).map do |n|
          if n == 0
            0
          else
            50 * (2 ** (n - 1)) / 1000.0
          end
        end

      end