public static <T> MergingRangeMap<T> unit(T identity, BinaryOperator<T> merger) {
    return create(0, 1, identity, merger);
  }
Returns a new range map with {@code identity} from {@code [0, 1)} and {@code merger} as the default merging
function for {@link #put(Range, Object)}.
planetiler-core/src/main/java/com/onthegomap/planetiler/util/MergingRangeMap.java