between inner and outter rings (Polygon/NultiPolygon) -- ref #2151https://github.com/mapbox/unpacker/issues/324
```txt
A polygon consists of one or more rings. A ring is a connected sequence of four or more
points that form a closed, non-self-intersecting loop. A polygon may contain multiple
outer rings. The order of vertices or orientation for a ring indicates which side of the ring
is the interior of the polygon. The neighborhood to the right of an observer walking along
the ring in vertex order is the neighborhood inside the polygon. Vertices of rings defining
holes in polygons are in a counterclockwise direction. Vertices for a single, ringed
polygon are, therefore, always in clockwise order. The rings of a polygon are referred to
as its parts.
```
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