[Seaside] Someone explain please the following syntax that appear as illustration of jQuery

[Fritz Schenk]

<snip>
"From ..javascript/jquery/ajaxanddommanipulation "
JQAjaxFunctionalTest>>renderContentOn: html
   html code id: #logger; with: DateAndTime now.
   html paragraph: [
      html submitButton
         onClick: (html jQuery ajax
            script: [ :s | s << (s jQuery: #logger) html: DateAndTime now ]);
         with: 'Replace'.
      html submitButton
         onClick: (html jQuery ajax
            script: [ :s | s << (s jQuery: #logger) prepend: DateAndTime now ]);
         with: 'Prepend'.
      html submitButton
         onClick: (html jQuery ajax
            script: [ :s | s << (s jQuery: #logger) append: DateAndTime now ]);
         with: 'Append' ]
"Source"

<code id="logger">2010-12-21T18:56:27-08:00</code>
<p>
  <input id="id17" value="Replace" type="submit" class="submit"/>
  <input id="id19" value="Prepend" type="submit" class="submit"/>
  <input id="id21" value="Append" type="submit" class="submit"/>
</p>
</snip>

I have consulted various documentation text about the use of the '<<' command/ 
What is it?
Is there documentation for how jQuery for Seaside was architected?
Thanks