code: function _setupAdvanceOnHandler(selector) {
    return (event) => {
      if (this.isOpen()) {
        const targetIsEl = this.el && event.target === this.el;
        const targetIsSelector = !isUndefined(selector) && event.target.matches(selector);
  
        if (targetIsSelector || targetIsEl) {
          this.tour.next();
        }
      }
    };
  }
docs: Sets up the handler to determine if we should advance the tour
  @private