(Rails) Nokogiri从URL返回nil

def noko_scrape
  require 'nokogiri'
  require 'open-uri'
  url = "https://au.finance.yahoo.com/q/ta?s=ANZ.AX&t=2y"
  doc = Nokogiri::HTML(open(url))
  puts "Retrieved doc =" + doc[1..20]
  ...
def noko_scrape
  require 'nokogiri'
  require