> For the complete documentation index, see [llms.txt](https://ploegert.gitbook.io/til/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://ploegert.gitbook.io/til/programmy/clojure/argument-requirements-for-a-function.md).

# Argument Requirements For A Function

When defining a function, you must declare one or more function definitions, each of which will require a different set of arguments. These argument lists are stored as metadata for the function. So, if you are trying to figure out what arity a function is or what variations of arguments it takes, you can check the metadata like so:

```clojure
> (:arglists (meta #'str))
([] [x] [x & ys])
```

[source](http://stackoverflow.com/questions/1696693/clojure-how-to-find-out-the-arity-of-function-at-runtime)