Explicit Lifetime Annotations

Background

Lifetimes ensure references remain valid, preventing dangling pointers at compile time.

Problem

Write a function that returns a reference with explicit lifetime annotations to satisfy the borrow checker.

Input

References with lifetimes

Output

Valid reference with correct lifetime

Sample tests

Input: longest("a", "ab")

Expected: "ab"

Your solution

Learning objective

Master Rust lifetimes and reference validity