Refactor app.py: reorganize imports, remove unused code, and enhance readability

app.py

@@ -1,17 +1,24 @@
+from __future__ import annotations
+
+import math
 import os
 import pickle
 import re
+from abc import abstractmethod
 from collections import Counter
 from dataclasses import dataclass
-from typing import Callable, Dict, Iterable, List, Optional, Type, TypeVar
+from typing import Callable, Dict, Iterable, List, Optional, Type, TypedDict, TypeVar
 
+import gradio as gr
 import nltk
 import tqdm
+from nltk.corpus import stopwords as nltk_stopwords
 
 from nlp4web_codebase.ir.data_loaders.dm import Document
+from nlp4web_codebase.ir.data_loaders.sciq import load_sciq
+from nlp4web_codebase.ir.models import BaseRetriever
 
 nltk.download("stopwords", quiet=True)
-from nltk.corpus import stopwords as nltk_stopwords
 
 LANGUAGE = "english"
 word_splitter = re.compile(r"(?u)\b\w\w+\b").findall
@@ -144,19 +151,9 @@ def run_counting(
     )
 
 
-from nlp4web_codebase.ir.data_loaders.sciq import load_sciq
-
 sciq = load_sciq()
 counting = run_counting(documents=iter(sciq.corpus), ndocs=len(sciq.corpus))
 
-from __future__ import annotations
-
-import math
-from dataclasses import dataclass
-from typing import Iterable, List, Optional, Type
-
-from nlp4web_codebase.ir.data_loaders.dm import Document
-
 
 @dataclass
 class BM25Index(InvertedIndex):
@@ -251,11 +248,6 @@ bm25_index = BM25Index.build_from_documents(
 )
 bm25_index.save("output/bm25_index")
 
-from abc import abstractmethod
-from typing import Type
-
-from nlp4web_codebase.ir.models import BaseRetriever
-
 
 class BaseInvertedIndexRetriever(BaseRetriever):
     @property
@@ -362,10 +354,6 @@ bm25_index = BM25Index.build_from_documents(
     b=best_b,
 )
 
-from typing import TypedDict
-
-import gradio as gr
-
 
 class Hit(TypedDict):
     cid: str