To make the default value of `auto_tagging` to be true, the `if` statement is preferable to be

```ruby
if Settings.try(:graph).try(:auto_tagging) || Settings.try(:graph).try(:auto_tagging).nil?
```

so that it will be true even if users do not define this value at config/application.yml. 
I prefer a helper function to be defined at app/models/settings.rb.