Merge-EM Tweaks

[mharradon]

Clean some things up, demonstrate naming convention for cache fields in SFuncs.

[apfeffer]

Hi Michael,

All looks good, except that in Cat you've made original_range into __original_range. original_range is actually the user facing value, whereas range is internally calculated. So original_range should stay as is, I think, whereas range should become __range. A better solution would be to rename original_range with range, and range with __compiled_range.

[mharradon]

That's fine - I expected .range was user facing as many tests/algorithms refer to it rather than .original_range, so it seemed the de-facto interface.

My intent with non-dunderscored parameters is that they minimally define the SFunc input-output relation. It seems like deduplicated range serves that purpose better.

[jcampolongo]

As you mentioned, this is general cleanup (not really any tweaks) for readability, which is great.