function twentynineteen_get_discussion_data() {
  static $discussion, $post_id;

  $current_post_id = get_the_ID();
  if ( $current_post_id === $post_id ) {
    return $discussion; /* If we have discussion information for post ID, return cached object */
  } else {
    $post_id = $current_post_id;
  }

  $comments = get_comments(
    array(
      'post_id' => $current_post_id,
      'orderby' => 'comment_date_gmt',
      'order'   => get_option( 'comment_order', 'asc' ), /* Respect comment order from Settings » Discussion. */
      'status'  => 'approve',
      'number'  => 20, /* Only retrieve the last 20 comments, as the end goal is just 6 unique authors */
    )
  );

  $authors = array();
  foreach ( $comments as $comment ) {
    $authors[] = ( (int) $comment->user_id > 0 ) ? (int) $comment->user_id : $comment->comment_author_email;
  }

  $authors    = array_unique( $authors );
  $discussion = (object) array(
    'authors'   => array_slice( $authors, 0, 6 ),           /* Six unique authors commenting on the post. */
    'responses' => get_comments_number( $current_post_id ), /* Number of responses. */
  );

  return $discussion;
}