2 Checks for comparing to an empty slice such as `""` or `[]`,
3 and suggests using `.is_empty()` where applicable.
6 Some structures can answer `.is_empty()` much faster
7 than checking for equality. So it is good to get into the habit of using
8 `.is_empty()`, and having it is cheap.
9 Besides, it makes the intent clearer than a manual comparison in some contexts.