https://vsavkin.com/two-phases-of-angular-2-applications-fda2517604be
http://blog.scottlogic.com/2016/01/05/angular2-with-immutablejs.html
https://facebook.github.io/immutable-js/
Source: Immutable Design Pattern
TypeScript: ReadOnly modifier – https://basarat.gitbooks.io/typescript/content/docs/types/readonly.html