function linearRingss(flatCoordinates, offset, endss, stride) {
  let area = 0;
  for (let i = 0, ii = endss.length; i < ii; ++i) {
    const ends = endss[i];
    area += linearRings(flatCoordinates, offset, ends, stride);
    offset = ends[ends.length - 1];
  }
  return area;
}
@param {Array<number>} flatCoordinates Flat coordinates.
@param {number} offset Offset.
@param {Array<Array<number>>} endss Endss.
@param {number} stride Stride.
@return {number} Area.