Whats the proper way to write a Range next function

[Dennis]

On Wednesday, 15 June 2022 at 13:52:24 UTC, Christian Köstlin 
wrote:
> looks like there should be tons of annotations/attributes on it.

Because you have a template function, most attributes will be 
inferred based on the Range type. `const` is not inferred, but 
`popFront` mutates so it doesn't apply in your case. `@property` 
is not inferred either, but the spec says "Using property 
functions is not recommended until the definition is more certain 
and implementation more mature."