//START:wholefile
//START:addhovers
function addHovers(){
  //END:addhovers
  //START:variables
  var main_image = $("main_image");
  var main_caption = $("main_caption");
  var links = $$("#small_images a");
  //END:variables
  
  //START:links
  links.each(function(link){
  //END:links
  //START:link_observer
    link.cleanWhitespace();
    link.observe("mouseover", function(e){
      main_image.src = link.href;
      main_caption.innerHTML = link.firstChild.alt;
    })
  //END:link_observer  
  
  //START:links
  
  });
  //END:links
//START:addhovers  
}
//END:addhovers
//START:window_observer
Event.observe(window, "load", addHovers);
//END:window_observer
//END:wholefile