diff --git a/llmlingua/prompt_compressor.py b/llmlingua/prompt_compressor.py
index 3a6aecd..971c7ca 100644
--- a/llmlingua/prompt_compressor.py
+++ b/llmlingua/prompt_compressor.py
@@ -26,10 +26,10 @@
     TokenClfDataset,
     get_pure_token,
     is_begin_of_new_word,
-    replace_added_token,
-    seed_everything,
     process_structured_json_data,
     remove_consecutive_commas,
+    replace_added_token,
+    seed_everything,
 )
 
 
@@ -1279,7 +1279,6 @@ def sync_sentence(sentences, text):
 
         sentences = [nltk.sent_tokenize(c) for c in context]
         sentences = [sync_sentence(s, c) for s, c in zip(sentences, context)]
-        sentences = [sync_sentence(s, c) for s, c in zip(sentences, context)]
         dem_g, s2de, idx = defaultdict(set), defaultdict(int), 0
         for idx_d, s in enumerate(sentences):
             for _ in s:
diff --git a/llmlingua/utils.py b/llmlingua/utils.py
index ddba1cc..7b6681c 100644
--- a/llmlingua/utils.py
+++ b/llmlingua/utils.py
@@ -1,12 +1,12 @@
+import json
 import os
 import random
-import string
-import json
 import re
-import yaml
+import string
 
 import numpy as np
 import torch
+import yaml
 from torch.utils.data import Dataset