let node = svg.selectAll('.node')
            .data(graph.nodes)
            .enter().append('g')
                        .attr('class', 'node')
            .attr("data-toggle", "modal")
            .attr("data-target", "#myModal")
                        .call(d3.drag()
            .on("start", dragstarted)
            .on("drag", dragged)
            .on("end", dragended));;

        // creating a circle variable to call it afterward and redesign the colors
        let circle = node.append("circle")
     