What is this helper do?

[eluser]solid9[/eluser]
Hi guys

I just got the codes from this link below,
http://codeigniter.com/wiki/Add_Edit_Views

The helper codes,

Code:

function field($validation, $database = NULL, $last = ''){
$value = (isset($validation)) ? $validation : ( (isset($database)) ? $database : $last);
return $value;
}

Let me try to guess.
If $validation is set then do nothing
else if $database is not set do $last.

What is the use of $database if it is already auto-loaded?
And what the hell is $last do?

So in you opinion what does the codes do?

Thanks in advanced.