Redirect authenticated users away from /login

web/server.rb

   end
 
   get '/login' do
+    redirect '/' if signed_in?
     erb :login, { layout: :layout, locals: { error_message: nil } }
   end
 
   post '/login' do
+    redirect '/' if signed_in?
     username = params[:username]
     password = params[:password]
     cookie = login(username, password)