tr("cx", d => d.x);
        
        d3.selectAll("circle").on("mouseover", nodeOver);
        d3.selectAll("path").on("mouseover", edgeOver);
        function nodeOver(d) {
          d3.selectAll("circle").classed("active", p => p === d);
          d3.selectAll("path").classed("active", p => p.source === d
            || p.target === d);
        }
        function edgeOver(d) {
          d3.selectAll("path").classed("active", p => p === d);
          d3.selectAll("circle")
            .classed("source", p 