class ActiveModel::Serializer

def serializer_for(resource)
  if resource.respond_to?(:to_ary)
    if Object.constants.include?(:ArraySerializer)
      ::ArraySerializer
    else
      ArraySerializer
    end
  else
    begin
      Object.const_get "#{resource.class.name}Serializer"
    rescue NameError
      nil
    end
  end
end