code: function (e, shape, chart, series) {
              // Return the opacity of the marker
              d3.select(shape).style("opacity", (series.lineMarkers ? dimple._helpers.opacity(e, chart, series) : 0));
              if (chart._tooltipGroup !== null && chart._tooltipGroup !== undefined) {
                  chart._tooltipGroup.remove();
              }
          }
docs: Handle the mouse leave event