.compare(uncheckedCastNullableTToT(range.getLowerEndpoint()), node.getElement());
    if (cmp < 0) {
      return aggregateBelowRange(aggr, node.left);
    } else if (cmp == 0) {
      switch (range.getLowerBoundType()) {
        case OPEN:
          return aggr.nodeAggregate(node) + aggr.treeAggregate(node.left);
        case CLOSED:
          return aggr.treeAggregate(node.left);
      }
      throw new AssertionError();