```ruby
class RstudioPreview < Cask
  url 'https://s3.amazonaws.com/rstudio-dailybuilds/RStudio-0.98.770.dmg'
  homepage 'http://www.rstudio.com/ide/download/preview'
  version '0.98.770'
  sha256 'f2d9abf1abc624812f93dd2ea17371db89343f3aa1b06740312377302238e041'
  link 'RStudio.app'
end
```

Update RStudio preview to 0.98.806
user
```ruby
class RstudioPreview < Cask
  url 'https://s3.amazonaws.com/rstudio-dailybuilds/RStudio-0.98.806.dmg'
  homepage 'http://www.rstudio.com/ide/download/preview'
  version '0.98.806'
  sha256 'a6a20ef021c10d395aeeb1057a69d8da9e349a7aa9b6a9e44df76767299b22a5'
  link 'RStudio.app'
end
```
assistant