code: function onItemHovered(instance, itemUi) {
      if (instance._options.disabled || !isEnabledOptionUi(itemUi)) {
        return
      }
  
      if (instance._options.multiple) {
        if (instance._dragSelectionStartOption) {
          updateMultiSelection(instance, itemUi)
        }
        return
      }
  
      instance._root.setAttribute('data-szn-options--highlighting', '')
      const previouslyHighlighted = instance._root.querySelector('[data-szn-options--highlighted]')
      if (previouslyHighlighted) {
        previouslyHighlighted.removeAttribute('data-szn-options--highlighted')
      }
      itemUi.setAttribute('data-szn-options--highlighted', '')
    }
docs: Handles the user moving the mouse pointer over an option in the szn-options element's UI. The function updates the
  current multiple-items selection if the element represents a multi-select, or updates the currently highlighted
  item in the UI of a single-select.
  
  @param {SznElements.SznOptions} instance The szn-options element instance.
  @param {Element} itemUi The element which's area the mouse pointer entered.