S2LaxPolygonShape represents a region defined by a collection of zero or more closed loops. The interior is the region to the left of all loops. This is similar to S2Polygon::Shape except that this class supports polygons with degeneracies. Degeneracies are of two types: degenerate edges (from a vertex to itself) and sibling edge pairs (consisting of two oppositely oriented edges). Degeneracies can represent either "shells" or "holes" depending on the loop they are contained by. For example, a degenerate edge or sibling pair contained by a "shell" would be interpreted as a degenerate hole. Such edges form part of the boundary of the polygon.