def class attachment = nil, style_name = nil
      return super() if attachment.nil? && style_name.nil?
      attachment.instance.class.to_s.underscore.pluralize
    end
def class attachment = nil, style_name = nil
      return super() if attachment.nil? && style_name.nil?
      attachment.instance.class.to_s.underscore.pluralize
    end
Returns the underscored, pluralized version of the class name.
 e.g. "users" for the User class.
 NOTE: The arguments need to be optional, because some tools fetch
 all class names. Calling #class will return the expected class.