Resources
- https://fluffy.es/closure-overview/
- https://grokswift.com/completion-handler-faqs/
- http://alisoftware.github.io/swift/closures/2016/07/25/closure-capture-1/
- https://www.andrewcbancroft.com/2017/04/26/what-in-the-world-is-an-escaping-closure-in-swift/
- https://medium.com/@stremsdoerfer/understanding-memory-leaks-in-closures-48207214cba
- https://blog.bobthedeveloper.io/swift-capture-list-in-closures-e28282c71b95