```ruby
cask :v1 => 'sketch' do
  version :latest
  sha256 :no_check

  url 'http://bohemiancoding.com/static/download/sketch.zip'
  appcast 'http://www.bohemiancoding.com/sketch/appcast.xml'
  homepage 'http://www.bohemiancoding.com/sketch/'
  license :unknown    # todo: change license and remove this comment; ':unknown' is a machine-generated placeholder

  app 'Sketch.app'
end
```

Update Sketch.app to commercial license.
user
```ruby
cask :v1 => 'sketch' do
  version :latest
  sha256 :no_check

  url 'http://bohemiancoding.com/static/download/sketch.zip'
  appcast 'http://www.bohemiancoding.com/sketch/appcast.xml'
  homepage 'http://www.bohemiancoding.com/sketch/'
  license :commercial

  app 'Sketch.app'
end
```
assistant