code: function(subjectPolygon, clipPolygon) {
          var subj = subjectPolygon;
          if (!this.isClockwise(subj)) {
              subj = [].concat(subj).reverse();
          }
          var clip = clipPolygon;
          if (this.isClockwise(clip)) {
              clip = [].concat(clip).reverse();
          }
          var result = this._clipPolygon(subj, clip);
          return result;
      }
docs: Clips polygon by the specified bounding polygon (not a bounding box!).
  The subject and clipping polygons are closed "rings" or [x,y] coordinate
  arrays (the last and the first coordinates in each sequence should be the
  same).