Views Argument Handling Code - has someone the final piece of my puzzle

Hi

I have simplified this for the sake of example.

I want to make a view based on a value generated by PHP.

in my administer/views page I have pasted in argument handling code:

$args[0] = 3;

return $args;

And now I want to use that argument to filter the search results, so my filter looks something like this:

Filter: Node: Week_of_the_Year is Equal To $args[0]

but this does not work.

What is the correct way of referring to my generated argument?

Thankyou

James