```ruby
class Jing < Cask
  url 'http://download.techsmith.com/jing/mac/jing.dmg'
  homepage 'http://www.techsmith.com/jing.html'
  version 'latest'
  sha1 'no_checksum'
  link 'Jing.app'
end
```

Remove quotation marks for no_checksum
user
```ruby
class Jing < Cask
  url 'http://download.techsmith.com/jing/mac/jing.dmg'
  homepage 'http://www.techsmith.com/jing.html'
  version 'latest'
  no_checksum
  link 'Jing.app'
end
```
assistant