module Dry::Configurable::ClassMethods

def inherited(subclass)
  super
  subclass.instance_variable_set(:@__config_extension__, __config_extension__)
  new_settings = _settings.dup
  subclass.instance_variable_set(:@_settings, new_settings)
  # Only classes **extending** Dry::Configurable have class-level config. When
  # Dry::Configurable is **included**, the class-level config method is undefined because it
  # resides at the instance-level instead (see `Configurable.included`).
  if respond_to?(:config)
    subclass.instance_variable_set(:@config, config.dup_for_settings(new_settings))
  end
end