Pass document variable to subscript?

[wshuffman]

Is it possible to pass a document as an input item to a subscript?  I'm trying to edit our current holiday subscript to accept a holiday document.  This way we can have one holiday subscript and pass in the specific holiday table document and return the true/false holiday value.  Ultimately I'd like to find a way to check if a document was passed in and if not then use a default.  If that part isn't possible I can just always pass in the default.  I've tried to do it and the script fails when trying to access the passed in variable.  

[Anthony Holloway]

Yes you can pass a document.

Here's how I check for the document being passed in to my subflow, and use a default document if none was passed.  Note that default_calendar would contain a reference to a default file.

Set calendar = (calendar == null || calendar == DOC[]) ? default_calendar : calendar