if (node == null) {
      return 0;
    }
    // The cast is safe because we call this method only if hasLowerBound().
    int cmp =
        comparator()
            .compare(uncheckedCastNullableTToT(range.getLowerEndpoint()), node.getElement());
    if (cmp < 0) {
      return aggregateBelowRange(aggr, node.left);
    } else if (cmp == 0) {
      switch (range.getLowerBoundType()) {
        case OPEN: