code: function(polygons, clipPolygon) {
          var result = [];
          for (var i = 0; i < polygons.length; i++) {
              var r = this.clipPolygon(polygons[i], clipPolygon);
              if (r && r.length) {
                  result.push(r);
              }
          }
          return result;
      }
docs: Returns an interection of a list of polygons with the specified clip
  polygon