How to use the @instructure/ui-dom-utils.getActiveElement function in @instructure/ui-dom-utils

function scopeTab (element, event, onLeavingFinalTabbable) {
  const node = findDOMNode(element)
  const tabbable = findTabbable(node)

  if (!tabbable.length) {
    event.preventDefault()
    return
  }

  // Account for a changing tabindex of the active element
  // (a case that happens with Menu for KO a11y)
  if (containsActiveElement(element)) {
    const activeElement = getActiveElement()
    if (tabbable.indexOf(activeElement) === -1) {
      tabbable.push(activeElement)
    }
  }

  const finalTabbable = tabbable[event.shiftKey ? 0 : tabbable.length - 1]
  const leavingFinalTabbable = (
    isActiveElement(finalTabbable) ||
    // handle immediate shift+tab after opening with mouse
    isActiveElement(node) ||
    // already left final tabbable
    !containsActiveElement(element)
  )

  if (!leavingFinalTabbable) return

get activeElement () {
    return getActiveElement(this.doc)
  }