I'm a Ruby on Rails developer who has created three production-quality Ruby on Rails applications from scratch, and I have five years of experience with Ruby on Rails. I use test-driven development to guide my work. I've found RSpec,Capybara and Jest to be invaluable tools for this. To publish Ruby on Rails applications to the web, I've used many cloud technologies including Docker, Kubernetes, AWS EC2, RDS, S3, ECS, SES, ELB, and auto scaling.
You may or may not be familiar with Priceline's "Express Deals". Express Deals are discounted hotel rooms that come with a slight catch: you don't know exactly which hotel you're booking until after you've already paid, and they're non-refundable and non-cancellable.
The government of a country, or the Federal Reserve Bank in the case of the United States, is able to control the value of their currency. In the US, this is done by issuing Treasury Bonds at with higher or lower interest rates. Higher interest rates generate increased demand for American Treasury Bonds.