docs: def rename_file(self, instance, field_name):
          """
          Renames a file and updates the model field to point to the new file.
          Returns True if a change has been made; otherwise False
  
          """
          file = getattr(instance, field_name)
  
          if file:
              new_name = get_hashed_filename(file.name, file)
              if new_name != file.name:
                  print('    Renaming "%s" to "%s"' % (file.name, new_name))
                  file.save(os.path.basename(new_name), file, save=False)
                  return True
  
          return False