polish download pretrain model and add comments to the func

ppcls/utils/model_zoo.py

@@ -17,10 +17,10 @@ from __future__ import division
 from __future__ import print_function
 
 import os
-import shutil
 import requests
-import tqdm
+import shutil
 import tarfile
+import tqdm
 import zipfile
 
 from ppcls.utils.check import check_architecture
@@ -40,18 +40,6 @@ class UrlError(Exception):
         super(UrlError, self).__init__(message)
 
 
-class ModelNameError(Exception):
-    """ ModelNameError
-    """
-
-    def __init__(self, message='', architecture=''):
-        similar_names = similar_architectures(architecture)
-        model_list = ', '.join(similar_names)
-        message += '\n{} is not exist. \nMaybe you want: [{}]'.format(
-            architecture, model_list)
-        super(ModelNameError, self).__init__(message)
-
-
 class RetryError(Exception):
     """ RetryError
     """
@@ -172,7 +160,18 @@ def _decompress(fname):
 
 
 def get(architecture, path, decompress=True):
-    check_architecture(architecture)
+    """
+    Get the pretrained model.
+
+    Args:
+        architecture: the name of which architecture to get. 
+            If the name is not exist, will raises UrlError with error code 404.
+        path: which dir to save the pretrained model.
+        decompress: decompress the download or not.
+
+    Raises:
+        RetryError or UrlError if download failed
+    """
     url = _get_url(architecture)
     fname = _download(url, path)
     if decompress: _decompress(fname)