Yep, needs to do use convert_type
```
CRuby 1.9.3 >> class A
CRuby 1.9.3 ?>   end
CRuby 1.9.3 => nil
CRuby 1.9.3 >> rand(A.new)
TypeError: can't convert A into Integer
        from (irb):4:in `rand'
        from (irb):4
        from /home/tim/.rbenv/versions/ruby/bin/irb:12:in `<main>'
CRuby 1.9.3 >> class A
CRuby 1.9.3 ?>   def to_int
CRuby 1.9.3 ?>     10
CRuby 1.9.3 ?>     end
CRuby 1.9.3 ?>   end
CRuby 1.9.3 => nil
CRuby 1.9.3 >> rand(A.new)
CRuby 1.9.3 => 6
```