code: function createHelpTooltip() {
    if (helpTooltipElement) {
      helpTooltipElement.parentNode.removeChild(helpTooltipElement);
    }
    helpTooltipElement = document.createElement('div');
    helpTooltipElement.className = 'ol-tooltip hidden';
    helpTooltip = new Overlay({
      element: helpTooltipElement,
      offset: [15, 0],
      positioning: 'center-left'
    });
    map.addOverlay(helpTooltip);
  }
docs: Creates a new help tooltip