You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: delegator.rb
    path of file: ./repos/stackneveroverflow/vendor/bundle/ruby/2.3.0/gems/devise-4.3.0/lib/devise
    
    the code of the file until where you have to start completion: module Devise
  # Checks the scope in the given environment and returns the associated failure app.
  class Deleg
    
    def failure_app(env)
      app = env["warden.options"] &&
        (scope = env["warden.options"][:scope]) &&
        Devise.mappings[scope.to_sym].failure_app

      app || Devise::FailureApp
    end