_.last

The last item in a list is something you actually need in Comfy: the final frame of a batch, the newest filename in a list, the last seed generated. _.last gets it for you with one input and zero ceremony. The only wrinkle is the n parameter, and it's a wrinkle that has bitten more than a few people.

What it is

Part of the ovum/underscore family in sfinktah/comfy-ovum, wrapping the last method of underscore3, a Python port of Underscore.js. No iteratee, no shorthand, no cleverness: return the last element, or the last n elements.

Inputs and outputs

• py_list (type *) - the list. The generator names array-ish inputs py_list; any JSON-serializable value works.
• n (INT, default 1) - how many elements to take from the tail.

Output is one value, typed * (ANY). Feed a _.CHAIN and you get a chain back for continued chaining, resolved with _.value.

The trap in n

Default n=1 returns the last element itself - a scalar. But set n to anything, including 1, and you get a list of the last n elements. Yes, n=1 is different from the default of 1. That's faithful to Underscore.js semantics, and the port's own docs call it out, but it still catches people: they set n=1 thinking they're being explicit, and suddenly their scalar input is a one-element list and a strict node downstream throws a fit. If you want a single element, leave n alone. If you want a slice of the tail, set n - and expect a list.

Where it earns its place

Batch tails, mostly. Last frame in a video batch, last item after a sort, the newest of a set of paths. Pair it with _.max-style logic and you can grab the "winning" element after ranking. It's small, but it removes a whole class of "index from the end" arithmetic that Python makes awkward without negative indexing.

Installing comfy-ovum

ComfyUI Manager: search for comfy-ovum, install, restart. Or by hand:

cd ComfyUI/custom_nodes
git clone https://github.com/sfinktah/comfy-ovum
pip install -r comfy-ovum/requirements.txt

Restart and you're done. No model downloads, no CUDA - pure-Python utilities. Family caveat: the README calls these nodes a work in progress. _.last is low-risk in practice; just keep that n quirk in mind and you're fine.