fn annotation_family_of_keys<'a>(
keys: impl Iterator<Item = &'a str>,
) -> Result<Option<AnnotationFamily>>Expand description
Classifies a SET/UNSET key batch: Ok(Some(family)) when every key belongs
to the same annotation family, Ok(None) when none does, and an error on a
mixed batch — annotation alters skip region dispatch, so they cannot share
a statement with options that regions must see.