The Monastery's moral equivalent of an "edit button" involves a couple steps (but ONLY for a registered Monk -- AM's need not apply):

1. open the node you wish to edit (so it's the top item in the browser window or tab)
2. scroll down below the formatted version of what you originally entered to see --
               ...VOILA!
   a text-entry box (just like the one where you entered your original)
3. Edit -- DO NOT DELETE WHAT YOU'VE POSTED -- simply use <strike>...</strike> around anything you wish to disavow (code: add a comment in the erroneously posted code or create a new code block and put the strike tags outside the original code tags). Be sure to add a note -- something like "<p><b>UPDATE: </b> (tell us here what you changed and, if relevant, why).</p>"
4. Use the "update" button but only after carefully reviewing the text-entry box because there is NO preview. I.e., if you screw it up, you'll have to edit again (albeit in the same window or tab)

When done, you may have something like this:

Initial narrative here. Blah, blah, blah, etc. and so forth....

 for $_(@foobar) {
    print $foo
}
[download]

UPDATE: Copy/paste error in OP (wrong var in first line; no semi-colon in Ln 2); correct code below:

<c> for my $foo(@foobar) {
    print $foo;
}
[download]

But, again, ya' gotta' register to make this work.