Example: <div id="mytarget">...</div>
<div id="test">
{{A('click
me',callback=URL('mycallback'),target="mytarget",delete="div#test")}}
</div>
when you click on mycallback the div#test disappears and the str
returned by the ajax mycallback is displayed in div#mytarget.
Useful for adding buttons to tables, for example:
db.table.id.represent = lambda id: {A('delete
me',callback=URL('delete_record',args=id),delete="tr")
