Add Argument Requirements For A Function as a clojure til.

README.md

@@ -29,6 +29,7 @@ smart people at [Hashrocket](http://hashrocket.com/).
 ### clojure
 
 - [Aggregation Using merge-with](clojure/aggregation-using-merge-with.md)
+- [Argument Requirements For A Function](clojure/argument-requirements-for-a-function.md)
 - [Evaluate One Liners With lein-exec](clojure/evaluate-one-liners-with-lein-exec.md)
 - [Expanding Macros](clojure/expanding-macros.md)
 - [Get The Value Of An Environment Variable](clojure/get-the-value-of-an-environment-variable.md)

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)