fix load param

deepspeech/utils/checkpoint.py

@@ -16,8 +16,8 @@ import json
 import os
 import re
 from pathlib import Path
-from typing import Union
 from typing import Text
+from typing import Union
 
 import paddle
 from paddle import distributed as dist
@@ -146,7 +146,7 @@ class Checkpoint():
         Returns:
             configs (dict): epoch or step, lr and other meta info should be saved.
         """
-        return self._load_parameters(model, optimizer, checkpoint_dir,
+        return self.load_parameters(model, optimizer, checkpoint_dir,
                                     checkpoint_path, "checkpoint_latest")
 
     def load_best_parameters(self,
@@ -166,7 +166,7 @@ class Checkpoint():
         Returns:
             configs (dict): epoch or step, lr and other meta info should be saved.
         """
-        return self._load_parameters(model, optimizer, checkpoint_dir,
+        return self.load_parameters(model, optimizer, checkpoint_dir,
                                     checkpoint_path, "checkpoint_best")
 
     def _should_save_best(self, metric: float) -> bool: