Slug: own-move-03 · Paired reading: Chapter 5
Prompt
Implement fn both_ends(s: &str) -> (String, String) returning owned copies of
the first and last character as one-char Strings (empty input → two empty Strings).
Prefer borrowing the input; clone/allocate only for the outputs.
Rust angle
Interviewers watch whether you clone out of panic or out of necessity.