```ruby
class Firefox < Cask
  url 'http://download.cdn.mozilla.net/pub/mozilla.org/firefox/releases/22.0/mac/en-US/Firefox%2022.0.dmg'
  homepage 'https://www.mozilla.org/en-US/firefox/'
  version '22.0'
  sha1 '45ef69d4254c725114c3fa8ffc5e5bef331e46bd'
  link 'Firefox.app'
end
```

Change to latest version of Firefox
user
```ruby
class Firefox < Cask
  url 'https://download.mozilla.org/?product=firefox-latest&os=osx&lang=en-US'
  homepage 'https://www.mozilla.org/en-US/firefox/'
  version 'latest'
  no_checksum
  link 'Firefox.app'
end
```
assistant