ch-ch-update: series, closed-form series, and strides

[Christopher Wright]

Andrei Alexandrescu wrote:
> The truth is, the reasons against using strings for short functions are 
> shrinking. I mean, you don't want to not use strings just to not use 
> strings, right? I hope I convinced you that strings are unbeatable for 
> short functions that don't need access to local state, their efficiency 
> is exemplary, and their error messages are not half bad.

Yes, but they don't interact with an IDE.