public static <T> MergingRangeMap<T> create(double lo, double hi, T identity, BinaryOperator<T> merger) {
    return new MergingRangeMap<>(lo, hi, identity, merger);
  }
Returns a new range map with {@code identity} from {@code [lo, hi)} and {@code merger} as the default merging
function for {@link #put(Range, Object)}.
planetiler-core/src/main/java/com/onthegomap/planetiler/util/MergingRangeMap.java