function change_option(number,index)
 { 
 for (var i = 1; i <= number; i++) 
 {
  document.getElementById('current' + i).className = ''; document.getElementById('content' + i).style.display = 'none'; } 
  document.getElementById('current' + index).className = 'current'; document.getElementById('content' + index).style.display = 'block'; }