public TileWeights put(TileCoord coord, long weight) {
    weights.merge(coord, weight, Long::sum);
    byZoom.merge(coord.z(), weight, Long::sum);
    return this;
  }
Adds {@code weight} to the current weight for {@code coord} and returns this modified instance.
planetiler-core/src/main/java/com/onthegomap/planetiler/util/TileWeights.java