function openClose(div_id1, div_id2) {
  if (document.getElementById(div_id2).style.display == 'block') {
    var str = document.getElementById(div_id1).innerHTML;
    document.getElementById(div_id1).innerHTML = str.replace(/«/, "»");
    document.getElementById(div_id2).style.display = 'none';
  }
  else {
    var str = document.getElementById(div_id1).innerHTML;
    document.getElementById(div_id1).innerHTML = str.replace(/»/, "«");
    document.getElementById(div_id2).style.display = 'block';
  }
}