Tell if an OpenStreetMap element is an area or not.
First, decide if your element is a way or a relation. If it's neither, you're done cause hey, it's not an area!
If you are not so fortunate to have all your elements be nodes, look further...
An area must be a way or a relation. But not just any way or relation.
According to Overpass turbo, a way is considered an area if
1. It forms a closed loop
2. It is not tagged area=no
3. It conforms to one of the conditions for polygon tags.
```rust use osmisarea;
let tags = vec![ (r"waterway", r"riverbank") ]; let refs = vec![1, 3, 2, 1];
let isarea = osmisarea::way(&tags, &refs); asserteq!(true, is_area); ```
A relation is an area when it has a tag "type" with value "multipolygon". ```rust use osmisarea;
let tags = vec![ (r"type", r"multipolygon") ]; let members = vec![1, 3, 2, 1];
let isarea = osmisarea::relation(&tags, &members); asserteq!(true, is_area); ```
MIT