例：
foo is a tool used to do foo.
Download_
.. _Download: http://example.com/foo
blah blah blah (omit a lot of paragraphs)
bar is another tool to do bar.
Download_
.. _Download: http://example.com/bar
由于Download指向不同的URL，docutilus给出以下错误报告：
Duplicate target name, cannot be used as a
unique reference: "Download".
在降价促销中，我可以为这两个指定不同的ID Download：
[Download][download-foo]
[download-foo]: http://example.com/foo
[Download][download-bar]
[download-bar]: http://example.com/bar
如何在reStructuredText中做类似的事情？