sourcecode tag nesting

Hello,
I was wondering how examples on this page were formatted using [sourcecode] tag. There are three examples below the following sentence:

Here’s some examples of the above parameters in action:

that show [sourcecode] tag in action. In order to show these examples, I assume you copied first line with sourcecode tag and pasted it as first line (practically duplicating the first line), but whatever I tried to do with the last line – [/sourcecode], I couldn’t show it inside the formatted text, it was always parsed as closing tag.
So, I tried to post last example like this (in HTML editor of a new post in my WordPress blog):

[sourcecode language="html" padlinenumbers="4"]
[sourcecode language="html" padlinenumbers="4"]
<strong>This</strong> is a short snippit of code with padlinenumbers set to 4.
[/sourcecode]
[/sourcecode]

Everything was fine and identical to the page mentioned above, but the last line didn’t appear inside formatted text, it was shown below as normal text.
Could you please advise as to how you’ve done it?

Thanks.