code: function updateMultiSelection(instance, lastHoveredItem) {
      const startIndex = instance._dragSelectionStartOption.index
      const lastIndex = lastHoveredItem._option.index
      const minIndex = Math.min(startIndex, lastIndex)
      const maxIndex = Math.max(startIndex, lastIndex)
      const options = instance._options.options
      const additionalIndexes = instance._additionalSelectedIndexes
  
      for (let i = 0, length = options.length; i < length; i++) {
        const option = options.item(i)
        if (isOptionEnabled(option)) {
          let isOptionSelected = additionalIndexes.indexOf(i) > -1
          if (i >= minIndex && i <= maxIndex) {
            isOptionSelected = !instance._invertSelection
          }
          option.selected = isOptionSelected
        }
      }
  
      instance._options.dispatchEvent(new CustomEvent('change', {bubbles: true, cancelable: true}))
    }
docs: Updates the multiple-items selection. This function is meant to be used with multi-selects when the user is
  selecting multiple items by dragging the mouse pointer over them.
  
  Any item which's index is in the provided instance's list of additionally selected items will be marked as
  selected as well.
  
  @param {SznElements.SznOptions} instance The szn-options element instance.
  @param {Element} lastHoveredItem The element representing the UI of the last option the user has hovered using
  their mouse pointer.