mruby/mruby — pull request #2520 by mattn (2014-08-08 09:00:52+00:00)
Title: Add String#succ, String#succ!, String#next, String#next!

Added

* String#succ
* String#succ!
* String#next
* String#next!

So should work below.

```ruby
("aaaa".."matz").each_with_index do |s|
puts s
end
```