code: function handleHeadingKeydown(e) {
      eventUtils.handleLeftRightArrowsKeydown(e, () => {
          e.preventDefault();
          let index = getElementIndex(getHeadingEl(e, this.state.fake));
          const maxIndex = this.headingsEl.children.length - 1;
          const keyCode = e.charCode || e.keyCode;
          if (keyCode === 37) index = index === 0 ? maxIndex : index - 1;
          if (keyCode === 39) index = index === maxIndex ? 0 : index + 1;
  
          this.headingsEl.children[index].focus();
          if (this.state.activation === 'auto') this.processStateChange(index);
      });
      eventUtils.handleActionKeydown(e, () => {
          e.preventDefault();
          this.handleHeadingClick(e);
      });
  }
docs: Handle a11y for heading
  https://ebay.gitbooks.io/mindpatterns/content/disclosure/tabs.html
  @param {KeyboardEvent} e