New Swift features (5.1, 5.2)

Any new features we can make use of in this library?

#### 5.1
- https://www.hackingwithswift.com/articles/182/whats-new-in-swift-5-1
- https://www.raywenderlich.com/4187396-what-s-new-in-swift-5-1

#### 5.2
- https://swift.org/blog/swift-5-2-released/
- https://www.hackingwithswift.com/articles/212/whats-new-in-swift-5-2