Counting the number of things in a container

EDIT: Never mind – I got it. The term I need is ‘entries.’ “If the number of entries in L is 3” compiles and works.

I’m sure there’s a simple way to do this, but I’m not finding the syntax in the Documentation. I want to find out how many things are in a container. Some of the things in the container are scenery, so they won’t be moving, but there may be other (movable) things. If there is nothing in the container but the scenery bits, I want to have the Report rule give a non-default response, while if there IS something else, I’ll let the parser just mention the stuff that’s interesting.

Here’s the code that doesn’t work:

Report searching the urn:
	let L be the list of things in the urn;
	let M be the count of things in L;
	if M is 3:
		say "There's nothing in the urn but dirt, cigarette butts, and a sad palm tree.";
		rule succeeds.

I’ve tried it with “let M be the total of items in L,” all sorts of terms like that, but nothing I’ve tried compiles.

You can skip the list and just say

let N be the number of things in the urn;