Where can I download jQuery UI source code

Where can I download jQuery UI source code

I'm starting to read up on how to write a jQuery UI widget by reading:
"jQuery UI API Developer Guide" at http://jqueryui.com/docs/Developer_Guide,
"Understanding jQuery UI widgets: A tutorial" at
http://bililite.com/blog/understanding-jquery-ui-widgets-a-tutorial,
and
"A Plugin Development Pattern" at http://www.learningjquery.com/2007/10/a-plugin-development-pattern.
I'd find it really helpful to be able to look at the source code to
some jQuery UI widgets, but the only download page I've found so far
is "Build Your Download" at http://jqueryui.com/download, which
downloads minified JavaScript, which is REALLY not what you want if
your goal is to study the source code.
The unminified version must be available somewhere. Can anyone in
this group tell me where to find it?
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