def sender_class(sender)
      if sender.kind_of? Symbol
        reflections[sender.to_s].klass
      elsif sender.kind_of? ActiveRecord::Base
        sender.class
      else
        raise 'SimpleNotifications::SenderTypeError'
      end
    end
def sender_class(sender)
      if sender.kind_of? Symbol
        reflections[sender.to_s].klass
      elsif sender.kind_of? ActiveRecord::Base
        sender.class
      else
        raise 'SimpleNotifications::SenderTypeError'
      end
    end
Provides the class of Sender