create a build-in saver into trainer. A saver will automatically save checkpoint or predict model every `save_steps` training steps.
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@@ -510,6 +513,7 @@ class Trainer(object):
save_type: a string. The type of saved model. Currently support checkpoint(ckpt) and predict model(predict), default is ckpt. If both two types are needed to save, you can set as "ckpt,predict".