private SortKey accumulate(int value, int min, int levels) {
    possibleValues *= levels;
    if (possibleValues > MAX) {
      throw new IllegalArgumentException("Too many possible values: " + possibleValues);
    }
    result = (result * levels) + value - min;
    return this;
  }
Adds a new component {@code value} to the key.
planetiler-core/src/main/java/com/onthegomap/planetiler/util/SortKey.java