sub traverse {
  for my $element (@_) {
    if (Scalar::Util::blessed ($element)) {
      if (go_ahead($element)) {
        my @contents = $element->content_list() ;
        print "Before: ", @contents, "\n\n" ;
        traverse(@contents) ;
        print "After: ", @contents, "\n\n" ;
        $element->detach_content() ;
        $element->push_content (@contents) ;
      }
    }
    else {
      print "Processing a string: " ;
      $element = curly_quotes($element) ;
      print $element, "\n\n" ;
    }
  }
}