```ruby
require './config/environment'

class ApplicationController < Sinatra::Base

  configure do
    set :public_folder, 'public'
    set :views, 'app/views'
    enable :sessions
    set :session_secret, "secret_bookmark"
  end

  get '/' do
    erb :index
  end

  helpers do
    def logged_in?
      !!session[:user_id]
    end

    def current_user
      User.find_by_id(session[:user_id])
    end
  end
end
```

Update index route to redirect to users route if user is logged_in?
user
```ruby
require './config/environment'

class ApplicationController < Sinatra::Base

  configure do
    set :public_folder, 'public'
    set :views, 'app/views'
    enable :sessions
    set :session_secret, "secret_bookmark"
  end

  get '/' do
    if logged_in?
      redirect '/users'
    else
      erb :index
    end
  end

  helpers do
    def logged_in?
      !!session[:user_id]
    end

    def current_user
      User.find_by_id(session[:user_id])
    end
  end
end
```
assistant