```ruby
class Istumbler < Cask
  url 'http://istumbler.net/downloads/istumbler-99.zip'
  homepage 'http://istumbler.net/'
  version '99'
  sha1 '9dfdee3cc1405c4c01417ac0423473142c9b55c9'
  link 'iStumbler.app'
end
```

Upgrade iSumbler.app v100 GM Candidate 5
user
```ruby
class Istumbler < Cask
  url 'http://istumbler.net/beta/istumbler-100gmc5b.zip'
  homepage 'http://istumbler.net/'
  version '100gmc5b'
  sha1 '2afefb707f030cac94bc017650dff9f9d4b24bf4'
  link 'iStumbler.app'
end
```
assistant