new_contents: 
  class Environment(object):
  
      def __init__(self, loader, autoescape):
          pass
  
  def select_autoescape(files=[]):
      def autoescape(template_name):
          pass
      return autoescape
  
  class FileSystemLoader(object):
  
      def __init__(self, searchpath):
          pass
  
subject: Add missing test stub.