old_contents: print(id(1) == id(2))
  print(id(None) == id(None))
  print(id([]) == id([]))
  
  l = [1, 2]
  print(id(l) == id(l))
  
  f = lambda:None
  print(id(f) == id(f))
  
new_contents: print(id(1) == id(2))
  print(id(None) == id(None))
  # This can't be true per Python semantics, just CPython implementation detail
  #print(id([]) == id([]))
  
  l = [1, 2]
  print(id(l) == id(l))
  
  f = lambda:None
  print(id(f) == id(f))
  
subject: Fix unstable case in builtin_id.py test.