fix cache description again

mindspore/dataset/engine/datasets.py

@@ -2144,6 +2144,7 @@ class RepeatDataset(DatasetOp):
         """
         return self.count
 
+
 class SkipDataset(DatasetOp):
     """
     The result of applying Skip operator to the input Dataset.
@@ -2409,6 +2410,7 @@ class TransferDataset(DatasetOp):
     def stop_send(self):
         self.iterator.depipeline.StopSend()
 
+
 class RangeDataset(MappableDataset):
     """
     A source dataset that reads and parses datasets stored on disk in a range.
@@ -5319,6 +5321,7 @@ class BuildVocabDataset(DatasetOp):
 
         return new_op
 
+
 class BuildSentencePieceVocabDataset(DatasetOp):
     """
     Build a SentencePieceVocab from a dataset.

tests/ut/python/dataset/test_cache_map.py

@@ -24,6 +24,7 @@ DATA_DIR = "../data/dataset/testImageNetData/train/"
 
 GENERATE_GOLDEN = False
 
+
 def test_cache_map_basic1():
     """
     Test mappable leaf with cache op right over the leaf
@@ -177,6 +178,7 @@ def test_cache_map_failure1():
     assert num_iter == 0
     logger.info('test_cache_failure1 Ended.\n')
 
+
 if __name__ == '__main__':
     test_cache_map_basic1()
     logger.info("test_cache_map_basic1 success.")