code: def with_deprecation_warning(fn, extra_message=''):
    
    def new_fn(*args, **kwargs):
      if extra_message not in _DONE_WARN:
        tf.logging.warning(
            'Sonnet nest is deprecated. Please use '
            'tf.contrib.framework.nest instead. '
            + extra_message
        )
        _DONE_WARN[extra_message] = True
      return fn(*args, **kwargs)
    return new_fn
docs: Wraps the function and prints a warn-once (per `extra_message`) warning.