string literals; why not.

app/controllers/accounts_controller.rb

@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class AccountsController < ApplicationController
   before_action :set_account, only: [:show, :edit, :reveal, :update, :destroy]
 

app/controllers/application_controller.rb

@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class ApplicationController < ActionController::Base
   protect_from_forgery with: :exception
 

app/controllers/auth_controller.rb

@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class AuthController < ApplicationController
   skip_before_action :verify_session