Yes shr 1 is divide by 2. It looks like the function does what you would except
at O(log n). But...
The O(log n) stuff works in theory, but in practice memory access and cache
hotness have bigger
impact on performance. I don't think it's that useful to specify this.
[http://www.brendangregg.com/blog/2017-05-09/cpu-utilization-is-wrong.html](http://www.brendangregg.com/blog/2017-05-09/cpu-utilization-is-wrong.html)
Always measure!
The main thing I like about Nim is that I can always make some thing faster...
there are no limits.
But you got to measure!
