如何解析用户对象以返回屏幕名称并继续下一步操作

我正在学习代码cademy，我正在rubygem中学习twittrapi的第二步（我认为它被调用了）。。。我轻松完成了第一步。这是第二节课的内容。。。

verify_credentials.json端点的响应包含成功请求的身份验证用户的json编码表示。现在您将解析API响应并打印出当前用户的屏幕名称。

添加用于将HTTP响应解码为Ruby对象的代码。为此：

说明（这些是他们的说明）

添加json包的依赖项（哪个json包？）访问HTTP响应主体（我该怎么做？）解码JSON编码的响应请确保将解析的响应分配给用户变量！？

（我甚至读了他们给我的提示……在下面）

提示

可以通过将require"添加到源文件的顶部来添加依赖项。（我应该添加什么包？）

响应变量将具有一个名为body的属性，该属性包含HTTP响应的文本。

您可以调用JSON.parse来解码JSON编码的字符串。此方法返回一个已解码的对象。

我尝试了我认为正确的代码，但结果是不正确的。我需要输入什么才能使我的课程取得成功？下面是他们给我的代码：

require 'rubygems'
require 'oauth'
# Parse a response from the API and return a user object.
def parse_user_response(response)
  user = nil
  # Check for a successful request
  if response.code == '200'
    # Parse the response body, which is in JSON format.
    # ADD CODE TO PARSE THE RESPONSE BODY HERE
    user = 
    # Pretty-print the user object to see what data is available.
    puts "Hello, #{user["screen_name"]}!"
  else
    # There was an error issuing the request.
    puts "Expected a response of 200 but got #{response.code} instead"
  end
  user
end
# All requests will be sent to this server.
baseurl = "https://api.twitter.com"
# Verify credentials returns the current user in the body of the response.
address = URI("#{baseurl}/1.1/account/verify_credentials.json")
# Set up HTTP.
http             = Net::HTTP.new address.host, address.port
http.use_ssl     = true
http.verify_mode = OpenSSL::SSL::VERIFY_PEER
# If you entered your credentials in the previous
# exercise, no need to enter them again here. The
# ||= operator will only assign these values if
# they are not already set.
consumer_key ||= OAuth::Consumer.new "ENTER IN EXERCISE 1", ""
access_token ||= OAuth::Token.new "ENTER IN EXERCISE 1", ""
# Issue the request.
request = Net::HTTP::Get.new address.request_uri
request.oauth! http, consumer_key, access_token
http.start
response = http.request(request)
user = parse_user_response(response)

请尽可能提供帮助。感谢您的时间和考虑。：）