I'm pretty much a newbie at php (at the "install an app and try to tweak it a bit" stage). Is there a tool anywhere which can take a script which is spread over many files and show you all the code which is processed (for a given set of arguments passed to the script) in a single output?

For example, I want to make a call to zen cart from a script in a different language, which returns a category listing without any surrounding page. So I want to be able to trace what the actual process is to generate that then strip off all the unwanted bits to create a custom script.