def find_custom(controller)
      raise "This specification has no custom :find attribute" unless find
      find.is_a?(Proc) ? controller.instance_exec(&find) : controller.send(find)
    end
def find_custom(controller)
      raise "This specification has no custom :find attribute" unless find
      find.is_a?(Proc) ? controller.instance_exec(&find) : controller.send(find)
    end
finds the resource using the custom :find Proc or symbol