code: function getTooltipPosition([mouseX, mouseY]) {
              let tooltipX, tooltipY;
  
              // show tooltip to the right
              if ((mouseX - tooltipWidth) < 0) {
                  // Tooltip on the right
                  tooltipX = tooltipWidth - 185;
              } else {
                  // Tooltip on the left
                  tooltipX = -205
              }
  
              if (mouseY) {
                  tooltipY = tooltipOffset.y;
                  // tooltipY = mouseY + tooltipOffset.y;
              } else {
                  tooltipY = tooltipOffset.y;
              }
  
              return [tooltipX, tooltipY];
          }
docs: Calculates the desired position for the tooltip
  @param  {Number} mouseX             Current horizontal mouse position
  @param  {Number} mouseY             Current vertical mouse position
  @return {Number[]}                  X and Y position
  @private