code: def labelPoints(self,
                      sr,
                      polygons,
                      ):
          
          url = self._url + "/labelPoints"
          params = {
              "f" : "json",
              "sr" : sr,
              "polygons": self.__geomToStringArray(geometries=polygons,
                                                   returnType="list")
          }
          return self._get(url=url, param_dict=params,
                              securityHandler=self._securityHandler,
                              proxy_url=self._proxy_url,
                             proxy_port=self._proxy_port)
docs: The labelPoints operation is performed on a geometry service resource. 
          The labelPoints operation calculates an interior point for each polygon 
          specified in the input array. These interior points can be used by 
          clients for labeling the polygons.
          
          Inputs:
              polygons - array of polygons whose label points are to be computed
                         (structured as JSON geometry objects returned by the 
                         ArcGIS REST API).
              sr - spatial reference of the input geometries WKID.