input: [Detail] Multi-polygon count [Geometry Type] Polygon [Description] 
output: If this source data contains multi-polygons, the number present. A multi-polygon is a geometry that consists of multiple polygons, such as a land mass that includes lakes or a lake that includes islands. These inner shapes are listed here as inner lines but can be called inner loops, holes, or cut-outs in other contexts. Note that multiple polygons that constitutes the geometry of a single feature can be treated either as a multi-polygon or as a set of polygons.