What were some of your biggest breakthroughs while learning D?

[Dylan Graham]

[Inspiration from this r/C_Programming 
post](https://www.reddit.com/r/C_Programming/comments/oeoq82/what_were_some_of_your_biggest_breakthroughs/)

What's something you learnt or realised, a habit you developed, 
something you read or project you worked on that helped 
accelerate your understanding and/or productivity in D?

For example, mixin templates finally clicking and you realise how 
to use them in your code base. Stuff like that.