I would suggest you to change the setter to

```ruby
def self.private_domains=(value)
  @private_domains = !!value
```

so that the getter can be

```ruby
def self.private_domains
  @private_domains != false
end
```

Even better, we probably don't need the getter, we can use a question method directly.

```ruby
def self.private_domains?
  @private_domains != false
end
```