code: def write_unregistered_file(date=None):
      
      delete_registered_file()
      if date is None:
          date = get_time()
      for f in constants.unregistered_files:
          if os.path.lexists(f):
              if os.path.islink(f):
                  # kill symlinks and regenerate
                  os.remove(f)
                  write_to_disk(f, content=str(date))
          else:
              write_to_disk(f, content=str(date))
docs: Write .unregistered out to disk