An S2LatLngRect represents a closed latitude-longitude rectangle. It is capable of representing the empty and full rectangles as well as single points. Note that the latitude-longitude space is considered to have a *cylindrical* topology rather than a spherical one, i.e. the poles have multiple lat/lng representations. An S2LatLngRect may be defined so that includes some representations of a pole but not others. Use the PolarClosure() method if you want to expand a rectangle so that it contains all possible representations of any contained poles.