mruby/mruby — pull request #1183 by h2so5 (2013-04-16 07:10:17+00:00)
Title: Add Proc#arity

Issue https://github.com/mruby/mruby/issues/1068

```bash
$ mirb
mirb - Embeddable Interactive Ruby Shell

This is a very early version, please test and report errors.
Thanks :)

> Proc.new {|a, b|}.arity
=> 2
> Proc.new {|a, *b|}.arity
=> -2
> Proc.new {|a, b = 0, c|}.arity
=> 2
>
```