Always make nullable states explicit in your code by leveraging Rust's type system. Use `Option` rather than sentinel values (like empty structs or default values) to represent potentially missing data. When handling options, prefer idiomatic patterns like `.map()` with `.unwrap_or()` for transforming with fallbacks. Consider specialized types like `NonZeroUsize` when values should never be null or zero. ```rust // Good: Return Option instead of empty PathBuf fn find_python_install() -> Option { // Return Some(path) when found, None otherwise } // Good: Idiomatic handling of nullable values snap.retention_period .map(Snapshot::from_snapshot) .unwrap_or(RetentionPeriod::Indefinite) // Good: Using specialized non-null type #[derive(Debug, Serialize, Eq, PartialEq, Clone, Copy)] pub struct LastCacheSize(pub(crate) NonZeroUsize); // Good: Explicit null representation in data structures struct LastCacheKey { column_name: String, value_map: HashMap, LastCacheState> } ``` When working with external libraries like Arrow, use appropriate null-checking methods (e.g., `is_valid()`) and handle null values consistently rather than treating them as error conditions.