//! Reverse geocoding index: binary format, reader, and builder.
//!
//! The index is a set of flat binary files optimized for mmap + binary search
//! queries. See `notes/reverse-geocoding-spec.md` for the full format specification.
//!
//! # Feature gates
//!
//! - `geocode-reader`: enables [`Reader`] and its S2 dependency.
//! - `commands`: enables the builder (implies `geocode-reader`).