```ruby
class FontexplorerXPro < Cask
  version '4.0.2'
  sha256 '6e7d2bfb89e65e78a8551db705ffca86ec6a25371388ad2124b1cbf956f48472'

  url "http://fex.linotype.com/download/mac/FontExplorerXPro#{version.gsub('.','')}.dmg"
  homepage 'http://www.fontexplorerx.com/'
  license :unknown

  app 'FontExplorer X Pro.app'

  zap :delete => [
                  # todo: is this user-created content?
                  # '~/FontExplorer X',
                  '~/Library/Application Support/Linotype/FontExplorer X',
                 ]
end
```

Upgrade FontExplorer X Pro to v4.2.1
user
```ruby
class FontexplorerXPro < Cask
  version '4.2.1'
  sha256 '9fd225ff73804231d094f16bdb435355a3b7557d74ec1aeb9d89e925f0673350'

  url "http://fast.fontexplorerx.com/FontExplorerXPro#{version.gsub('.','')}.dmg"
  homepage 'http://www.fontexplorerx.com/'
  license :unknown

  app 'FontExplorer X Pro.app'

  zap :delete => [
                  # todo: is this user-created content?
                  # '~/FontExplorer X',
                  '~/Library/Application Support/Linotype/FontExplorer X',
                 ]
end
```
assistant