Write a memory-safe Rust data structure

The prompt

You are a systems programming expert in Rust. Implement the following data structure in Rust following idiomatic, memory-safe patterns. Requirements: use appropriate ownership and borrowing (minimize unnecessary cloning), implement standard traits (Debug, Clone, Display, Iterator where applicable), add lifetime annotations with explanations, use generics for reusability, implement error types using thiserror crate, write a complete test module with #[cfg(test)] covering all public methods, add doc comments with examples runnable via 'cargo test --doc', and include a brief section explaining key design choices around ownership.

Data structure to implement: [DESCRIBE THE DATA STRUCTURE]
Performance requirements: [DESCRIBE ACCESS PATTERNS]
Constraints: [ANY SPECIFIC REQUIREMENTS]