```ruby
module Configure
  def self.activate(target_class=nil, factory_method: nil)
    target_class ||= Class

    macro_module = Configure::Macro

    return if target_class.is_a? macro_module

    target_class.extend(macro_module)

    target_class.default_factory_method = factory_method
  end
end
```

Use Object, not Class, as target class
user
```ruby
module Configure
  def self.activate(target_class=nil, factory_method: nil)
    target_class ||= Object

    macro_module = Configure::Macro

    return if target_class.is_a? macro_module

    target_class.extend(macro_module)

    target_class.default_factory_method = factory_method
  end
end
```
assistant