Add Argument Requirements For A Function as a clojure til.

clojure/argument-requirements-for-a-function.md

@@ -0,0 +1,14 @@
+# 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:
+
+```
+> (:arglists (meta #'str))
+([] [x] [x & ys])
+```
+
+[source](http://stackoverflow.com/questions/1696693/clojure-how-to-find-out-the-arity-of-function-at-runtime)