>       checkpoint = init_checkpoint_callback(logger)
tests/test_a_restore_models.py:82: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
tests/utils.py:235: in init_checkpoint_callback
    exp = logger.experiment
pytorch_lightning/logging/test_tube_logger.py:37: in experiment
    rank=self.rank,
.tox/py37/lib/python3.7/site-packages/test_tube/log.py:154: in __init__
    super().__init__(log_dir=log_dir, *args, **kwargs)
.tox/py37/lib/python3.7/site-packages/torch/utils/tensorboard/writer.py:199: in __init__
    self._get_file_writer()
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
self = <test_tube.log.Experiment object at 0x7f533d7c8b70>
[1m    def _get_file_writer(self):
        """Returns the default FileWriter instance. Recreates it if closed."""
        if self.rank > 0:
            return TTDummyFileWriter()
    
        if self.all_writers is None or self.file_writer is None:
>           if self.purge_step is not None:
E           AttributeError: 'Experiment' object has no attribute 'purge_step'
.tox/py37/lib/python3.7/site-packages/test_tube/log.py:504: AttributeError