# File lib/generators/devise_token_auth/install_generator.rb, line 49
    def include_controller_concerns
      fname = "app/controllers/application_controller.rb"
      line  = "include DeviseTokenAuth::Concerns::SetUserByToken"

      if File.exist?(File.join(destination_root, fname))
        if parse_file_for_line(fname, line)
          say_status("skipped", "Concern is already included in the application controller.")
        elsif is_rails_api?
          inject_into_file fname, after: "class ApplicationController < ActionController::API\n" do "include DeviseTokenAuth::Concerns::SetUserByToken\n"
          end
        else
          inject_into_file fname, after: "class ApplicationController < ActionController::Base\n" do "include DeviseTokenAuth::Concerns::SetUserByToken\n"
          end
        end
      else
        say_status("skipped", "app/controllers/application_controller.rb not found. Add 'include DeviseTokenAuth::Concerns::SetUserByToken' to any controllers that require authentication.")
      end
    end