* This is a function.
*
* @param {string} n - A string param
+ * @param {string} [o] - A optional string param
+ * @param {string} [d=DefaultValue] - A optional string param
* @return {string} A good string
*
* @example
* foo('hello')
*/
-function foo(n) {
+function foo(n, o, d) {
return n
}
```