### What it does
Checks for comparing to an empty slice such as `""` or `[]`,
and suggests using `.is_empty()` where applicable.

### Why is this bad?
Some structures can answer `.is_empty()` much faster
than checking for equality. So it is good to get into the habit of using
`.is_empty()`, and having it is cheap.
Besides, it makes the intent clearer than a manual comparison in some contexts.

### Example

```
if s == "" {
    ..
}

if arr == [] {
    ..
}
```
Use instead:
```
if s.is_empty() {
    ..
}

if arr.is_empty() {
    ..
}
```