Project Elvis

[codephantom]

On Friday, 10 November 2017 at 05:23:53 UTC, Adam Wilson wrote:
> MSFT spends a LOT of time studying these things. It would be 
> wise to learn for free from the money they spent.

This is valid MSFT code, I believe:

A?.B?.C?[0] ?? E
A?.B?.C?[0] == E

I have been coding on and off, since 1992, in various languages.

So can you please tell what this code means?

Can you please tell me what it was that MSFT learnt (and spent 
money to do so), so as to enable coders to write such code?