text: Title: default_factory doesn't work
  Body: Hi! 
  I use default_factory to initialize my variable, but variable always returns the same result. It seems like default_factory doesn't work and it returns always the same result of function.
  
  Here is example to reproduce:
  https://play.strawberry.rocks/?gist=a7a5e62ffe4e68696b44456398d11104