What is your favorite D feature? [Call for snippets]

[Mike via Digitalmars-d]

On Thursday, 22 June 2017 at 07:10:14 UTC, Seb wrote:

> Nice list, but I was actually looking for more concise, 
> actionable snippets or idea(s) for such.

There are some real gems in this DConf Talk: 
https://www.youtube.com/watch?v=yMNMV9JlkcQ

I started enumerating them on the Wiki here 
(https://wiki.dlang.org/Tutorials#Design_Patterns) but alas it's 
still incomplete.

Mike