[MarkLogic Dev General] Newbie: Undefined function input()

[Steve]

I'm new to MarkLogic and I am using the online 'Getting Started'
documents to ease myself in.

However I've come across a problem that I can't find the solution to.
I'm trying to execute the following code:

for $i in input() return document-uri($i)

However, when running, I'm getting a '500 Internal Server Error':

500 Internal Server Error

XDMP-UNDFUN: (err:XPST0017) Undefined function input()
in /view.xqy, on line 9 [1.0-ml]

[line 9 refers to the code above.]


If anyone can shed some light on what I am doing wrong, I would be
very grateful.

Thanks

Steve