  *
     * @param {Node} anchor     Anchor element for positioning
     * @param {string} position One of: top/right/bottom
     * @param {Node} elem       Element to position
     *
     * Both elements: elem and anchor must be in the document
     */
    function positionAt(anchor, position, elem) {
      // ... your code ...
    }

    /**
     * Shows a note with the given html at the given position
     * relative to the anchor element.
     */
    function showNote(anchor, position, html) {

      let