code: function _makeCenteredTippy() {
    const tippyOptions = {
      content: this.el,
      placement: 'top',
      ...this.options.tippyOptions
    };
  
    tippyOptions.arrow = false;
    tippyOptions.popperOptions = tippyOptions.popperOptions || {};
  
    const finalPopperOptions = Object.assign(
      {},
      defaultPopperOptions,
      tippyOptions.popperOptions,
      {
        modifiers: Object.assign(
          centeredStylePopperModifier,
          tippyOptions.popperOptions.modifiers
        )
      }
    );
  
    tippyOptions.popperOptions = finalPopperOptions;
  
    return tippy(document.body, tippyOptions);
  }
docs: Generates a `Tippy` instance for a tooltip that doesn't have a
  target element in the DOM -- and thus is positioned in the center
  of the view
  
  @return {tippy} The final tippy instance
  @private