_onKeyPress (event) {
    if (event.keyCode === 39) {
      this.showNext(event);
    } else if (event.keyCode === 37) {
      this.showPrevious(event);
    }
  }
Reacts to specific keyboard commands to enable viewing a differnt item
in the gallery
@param  {Object} event The incoming keypress event
@return {void}