fn sniff_compaction<'a, T: Timestamp + Lattice>(
diffs: &'a [StateFieldDiff<HollowBatch<T>, ()>],
) -> Option<(Vec<&'a HollowBatch<T>>, HollowBatch<T>)>
fn sniff_compaction<'a, T: Timestamp + Lattice>(
diffs: &'a [StateFieldDiff<HollowBatch<T>, ()>],
) -> Option<(Vec<&'a HollowBatch<T>>, HollowBatch<T>)>