Ruby Koans：这个返回值的引号在哪里？

class Dog7
  attr_reader :name

  def initialize(initial_name)
    @name = initial_name
  end

  def get_self
    self
  end

  def to_s
    __
  end

  def inspect
    "<Dog named '#{name}'>"
  end
end

def test_inside_a_method_self_refers_to_the_containing_object
  fido = Dog7.new("Fido")

  fidos_self = fido.get_self
  assert_equal "<Dog named 'Fido'>",fidos_self
end

def test_to_s_provides_a_string_version_of_the_object
  fido = Dog7.new("Fido")
  assert_equal __,fido.to_s
end

第一个assert_equal的前半部分是我要填写的内容.此代码给出了错误：

<"<Dog named 'Fido'>"> expected but was  <<Dog named 'Fido'>>.

问题是,我坚持如何匹配返回值.它看起来像一个字符串字面值返回值,但我不知道如何表达,而不使用引号,和/或反斜杠.没有什么我尝试似乎工作.

帮帮我？