diff --git a/gnes/__init__.py b/gnes/__init__.py
index 967f5db1..82f2e316 100644
--- a/gnes/__init__.py
+++ b/gnes/__init__.py
@@ -14,7 +14,6 @@
 #  limitations under the License.
 
 
-
 # do not change this line
 # this is managed by git tag and replaced on every release
 __version__ = '0.0.27'
diff --git a/gnes/client/benchmark.py b/gnes/client/benchmark.py
index 17812682..1816ee3e 100644
--- a/gnes/client/benchmark.py
+++ b/gnes/client/benchmark.py
@@ -14,8 +14,6 @@
 #  limitations under the License.
 
 
-import time
-
 import grpc
 
 from ..helper import TimeContext
diff --git a/gnes/encoder/audio/mfcc.py b/gnes/encoder/audio/mfcc.py
index 3cd99959..79af1dee 100644
--- a/gnes/encoder/audio/mfcc.py
+++ b/gnes/encoder/audio/mfcc.py
@@ -14,7 +14,6 @@
 #  limitations under the License.
 
 
-
 from typing import List
 
 import numpy as np
diff --git a/gnes/encoder/numeric/hash.py b/gnes/encoder/numeric/hash.py
index a1fe8d22..ad5e400f 100644
--- a/gnes/encoder/numeric/hash.py
+++ b/gnes/encoder/numeric/hash.py
@@ -14,8 +14,6 @@
 #  limitations under the License.
 
 
-
-
 import numpy as np
 
 from ..base import BaseNumericEncoder
diff --git a/gnes/encoder/numeric/pca.py b/gnes/encoder/numeric/pca.py
index e77e6dda..970730d5 100644
--- a/gnes/encoder/numeric/pca.py
+++ b/gnes/encoder/numeric/pca.py
@@ -14,8 +14,6 @@
 #  limitations under the License.
 
 
-
-
 import numpy as np
 
 from ..base import BaseNumericEncoder
diff --git a/gnes/encoder/numeric/pq.py b/gnes/encoder/numeric/pq.py
index de93e309..73557a51 100644
--- a/gnes/encoder/numeric/pq.py
+++ b/gnes/encoder/numeric/pq.py
@@ -14,8 +14,6 @@
 #  limitations under the License.
 
 
-
-
 import numpy as np
 
 from ..base import BaseBinaryEncoder
diff --git a/gnes/encoder/numeric/tf_pq.py b/gnes/encoder/numeric/tf_pq.py
index 682c2808..8a302a33 100644
--- a/gnes/encoder/numeric/tf_pq.py
+++ b/gnes/encoder/numeric/tf_pq.py
@@ -14,8 +14,6 @@
 #  limitations under the License.
 
 
-
-
 from typing import Dict, Any
 
 import numpy as np
diff --git a/gnes/encoder/numeric/vlad.py b/gnes/encoder/numeric/vlad.py
index 48509f60..39664aeb 100644
--- a/gnes/encoder/numeric/vlad.py
+++ b/gnes/encoder/numeric/vlad.py
@@ -14,8 +14,6 @@
 #  limitations under the License.
 
 
-
-
 import copy
 
 import numpy as np
diff --git a/gnes/encoder/text/bert.py b/gnes/encoder/text/bert.py
index 75304907..a3cc1b9f 100644
--- a/gnes/encoder/text/bert.py
+++ b/gnes/encoder/text/bert.py
@@ -14,8 +14,6 @@
 #  limitations under the License.
 
 
-
-
 from typing import List
 
 import numpy as np
diff --git a/gnes/encoder/text/elmo.py b/gnes/encoder/text/elmo.py
index ce989ae3..9e0eba51 100644
--- a/gnes/encoder/text/elmo.py
+++ b/gnes/encoder/text/elmo.py
@@ -14,8 +14,6 @@
 #  limitations under the License.
 
 
-
-
 from typing import List
 
 import numpy as np
diff --git a/gnes/encoder/text/flair.py b/gnes/encoder/text/flair.py
index 7647113c..e9f61680 100644
--- a/gnes/encoder/text/flair.py
+++ b/gnes/encoder/text/flair.py
@@ -14,8 +14,6 @@
 #  limitations under the License.
 
 
-
-
 from typing import List
 
 import numpy as np
diff --git a/gnes/encoder/text/w2v.py b/gnes/encoder/text/w2v.py
index 7d9033ec..80231dd9 100644
--- a/gnes/encoder/text/w2v.py
+++ b/gnes/encoder/text/w2v.py
@@ -14,8 +14,6 @@
 #  limitations under the License.
 
 
-
-
 from typing import List
 
 import numpy as np
diff --git a/gnes/indexer/fulltext/leveldb.py b/gnes/indexer/fulltext/leveldb.py
index 633a7f4e..6323bfac 100644
--- a/gnes/indexer/fulltext/leveldb.py
+++ b/gnes/indexer/fulltext/leveldb.py
@@ -14,8 +14,6 @@
 #  limitations under the License.
 
 
-
-
 import pickle
 from threading import Thread, Event
 from typing import List, Any
diff --git a/gnes/indexer/vector/annoy.py b/gnes/indexer/vector/annoy.py
index 1e97ffc1..a3a888fe 100644
--- a/gnes/indexer/vector/annoy.py
+++ b/gnes/indexer/vector/annoy.py
@@ -72,14 +72,14 @@ def query(self, keys: 'np.ndarray', top_k: int, *args, **kwargs) -> List[List[Tu
 
     def normalize_score(self, score: List[float], metrics: str, *args, **kwargs) -> List[float]:
         if metrics == 'angular':
-            return list(map(lambda x:1 / (1 + x), score))
+            return list(map(lambda x: 1 / (1 + x), score))
         elif metrics == 'euclidean':
             import math
-            return list(map(lambda x:1 / (1 + math.sqrt(x) / self.num_dim), score))
+            return list(map(lambda x: 1 / (1 + math.sqrt(x) / self.num_dim), score))
         elif metrics == 'manhattan':
-            return list(map(lambda x:1 / (1 + x / self.num_dim), score))
+            return list(map(lambda x: 1 / (1 + x / self.num_dim), score))
         elif metrics == 'hamming':
-            return list(map(lambda x:1 / (1 + x), score))
+            return list(map(lambda x: 1 / (1 + x), score))
         elif metrics == 'dot':
             raise NotImplementedError
 
diff --git a/gnes/indexer/vector/bindexer/__init__.py b/gnes/indexer/vector/bindexer/__init__.py
index 9a7935b5..4bb7e2dc 100644
--- a/gnes/indexer/vector/bindexer/__init__.py
+++ b/gnes/indexer/vector/bindexer/__init__.py
@@ -14,7 +14,6 @@
 #  limitations under the License.
 
 
-
 import os
 from typing import List, Tuple, Any
 
diff --git a/gnes/indexer/vector/faiss.py b/gnes/indexer/vector/faiss.py
index e242e0bf..1f812de5 100644
--- a/gnes/indexer/vector/faiss.py
+++ b/gnes/indexer/vector/faiss.py
@@ -14,8 +14,6 @@
 #  limitations under the License.
 
 
-
-
 import os
 from typing import List, Tuple, Any
 
diff --git a/gnes/indexer/vector/hbindexer/__init__.py b/gnes/indexer/vector/hbindexer/__init__.py
index 17de9ea6..42bb3d8c 100644
--- a/gnes/indexer/vector/hbindexer/__init__.py
+++ b/gnes/indexer/vector/hbindexer/__init__.py
@@ -14,7 +14,6 @@
 #  limitations under the License.
 
 
-
 import os
 from typing import List, Tuple, Any
 
diff --git a/gnes/indexer/vector/numpy.py b/gnes/indexer/vector/numpy.py
index 7878b3b1..8ae3219d 100644
--- a/gnes/indexer/vector/numpy.py
+++ b/gnes/indexer/vector/numpy.py
@@ -14,7 +14,6 @@
 #  limitations under the License.
 
 
-
 from typing import List, Tuple, Any
 
 import numpy as np
diff --git a/gnes/preprocessor/video/ffmpeg.py b/gnes/preprocessor/video/ffmpeg.py
index 9a9bc7a4..169dcac3 100644
--- a/gnes/preprocessor/video/ffmpeg.py
+++ b/gnes/preprocessor/video/ffmpeg.py
@@ -13,10 +13,11 @@
 #  See the License for the specific language governing permissions and
 #  limitations under the License.
 
+import random
 from typing import List
 
 import numpy as np
-import random
+
 from .base import BaseVideoPreprocessor
 from ..helper import get_video_frames, phash_descriptor
 from ...proto import gnes_pb2, array2blob
diff --git a/gnes/router/reduce/chunk_sum.py b/gnes/router/reduce/chunk_sum.py
index 14d159b4..fbce320e 100644
--- a/gnes/router/reduce/chunk_sum.py
+++ b/gnes/router/reduce/chunk_sum.py
@@ -13,8 +13,8 @@
 #  See the License for the specific language governing permissions and
 #  limitations under the License.
 
-from typing import List
 from collections import defaultdict
+from typing import List
 
 from ..base import BaseReduceRouter
 from ...proto import gnes_pb2
@@ -42,4 +42,4 @@ def apply(self, msg: 'gnes_pb2.Message', accum_msgs: List['gnes_pb2.Message'], *
             r.score = v
             r.score_explained = doc_score_explained[k]
 
-        super().apply(msg, accum_msgs)
\ No newline at end of file
+        super().apply(msg, accum_msgs)
diff --git a/gnes/router/reduce/doc_sum.py b/gnes/router/reduce/doc_sum.py
index fec0b90b..99e957ce 100644
--- a/gnes/router/reduce/doc_sum.py
+++ b/gnes/router/reduce/doc_sum.py
@@ -13,8 +13,8 @@
 #  See the License for the specific language governing permissions and
 #  limitations under the License.
 
-from typing import List
 from collections import defaultdict
+from typing import List
 
 from ..base import BaseReduceRouter
 from ...proto import gnes_pb2
@@ -52,4 +52,4 @@ def apply(self, msg: 'gnes_pb2.Message', accum_msgs: List['gnes_pb2.Message'], *
         msg.response.search.ClearField('topk_results')
         msg.response.search.topk_results.extend(final_fulltext_docs[:msg.response.search.top_k])
 
-        super().apply(msg, accum_msgs)
\ No newline at end of file
+        super().apply(msg, accum_msgs)