code: function getPointProps(svg) {
              let mousePos = d3Selection.mouse(svg);
  
              mousePos[0] -= margin.left;
              mousePos[1] -= margin.top;
  
              return {
                  closestPoint: voronoi.find(mousePos[0], mousePos[1]),
                  mousePos
              };
          }
docs: Calculates and returns
  @param {*} svg
  @return {Object}
  @private