', d => d.x)
            .attr('cy', d => d.y)
            .attr("r", 6);

            g.selectAll('text').data(root.descendants()).join('text')
            .attr("text-anchor", d => d.children ? "end" : "start")
            // note that if d is a child, d.children is undefined which is actually false! 
            .attr('x', d => d.x)
            .attr('y', d => d.y + (d.children ? -10 : 10))
            .text(d => d.data.name)
            .attr('writing-mode', 'vertical-rl')
            .attr('text-orient