'Checkpoint the model checkpoint into file.
You can also use `pickle` to do the job if you only work on Python.
The advantage of `load` and `save` (as compared to `pickle`) is that
the resulting file can be loaded from other MXNet language bindings.
One can also directly `load`/`save` from/to cloud storage(S3, HDFS)
Parameters
prefix : str
Prefix of model name.
Notes
- ``prefix-symbol.json`` will be saved for symbol.
- ``prefix-epoch.params`` will be saved for parameters.'

def save(self, prefix, epoch=None):

    if (epoch is None):
        epoch = self.num_epoch
    assert (epoch is not None)
    save_checkpoint(prefix, epoch, self.symbol, self.arg_params, self.aux_params)
