If you pass a mutable object into a method, the method gets a reference to that same object and you can mutate it to your heart's delight, but if you rebind the reference in the method, the outer scope will know nothing about it, and after you're done, the outer reference will still point at the original object.
If you pass an immutable object to a method, you still can't rebind the outer reference, and you can't even mutate the object.
CAUTION! By default, only master branch's builds could trigger deployments in Travis CI.
Say that you would like to host your static site on Amazon S3 with a custom domain and, of course, HTTPS.
AWS Lambda is an event-driven service that you can upload your code to it and run those code on-demand without having your own servers.
AWS DynamoDB is a fully managed key-value store (also document store) NoSQL database as a service provided by Amazon Web Services. Its pricing model is that you only pay for the throughput (read and write) you use instead of the storage usage and the running hours of database instances.