code: function _addCornerstoneEventListeners() {
    // Clear any listeners that may already be set
    _removeCornerstoneEventListeners();
  
    const cornerstone = external.cornerstone;
    const elementEnabledEvent = cornerstone.EVENTS.ELEMENT_ENABLED;
    const elementDisabledEvent = cornerstone.EVENTS.ELEMENT_DISABLED;
  
    cornerstone.events.addEventListener(elementEnabledEvent, addEnabledElement);
    cornerstone.events.addEventListener(
      elementDisabledEvent,
      removeEnabledElement
    );
  }
docs: Wires up event listeners for the Cornerstone#ElementDisabled and
  Cornerstone#ElementEnabled events.
  @private
  @method
  @returns {void}