diff --git a/examples/function_call_examples.py b/examples/function_call_examples.py
index be65678..94e3e71 100644
--- a/examples/function_call_examples.py
+++ b/examples/function_call_examples.py
@@ -1,4 +1,6 @@
 # Reference: https://openai.com/blog/function-calling-and-other-api-updates
+import json
+from pprint import pprint
 
 import openai
 
@@ -9,216 +11,223 @@
 #   python openai_api.py;
 #
 # Then configure the api_base and api_key in your client:
-openai.api_base = "http://localhost:8000/v1"
-openai.api_key = "none"
+openai.api_base = 'http://localhost:8000/v1'
+openai.api_key = 'none'
 
 
 def call_qwen(messages, functions=None):
-    print(messages)
+    print('input:')
+    pprint(messages, indent=2)
     if functions:
-        response = openai.ChatCompletion.create(
-            model="Qwen", messages=messages, functions=functions
-        )
+        response = openai.ChatCompletion.create(model='Qwen',
+                                                messages=messages,
+                                                functions=functions)
     else:
-        response = openai.ChatCompletion.create(model="Qwen", messages=messages)
-    print(response)
-    print(response.choices[0].message.content)
+        response = openai.ChatCompletion.create(model='Qwen',
+                                                messages=messages)
+    response = response.choices[0]['message']
+    response = json.loads(json.dumps(response,
+                                     ensure_ascii=False))  # fix zh rendering
+    print('output:')
+    pprint(response, indent=2)
+    print()
     return response
 
 
 def test_1():
-    messages = [{"role": "user", "content": "你好"}]
+    messages = [{'role': 'user', 'content': '你好'}]
     call_qwen(messages)
-    messages.append({"role": "assistant", "content": "你好！很高兴为你提供帮助。"})
+    messages.append({'role': 'assistant', 'content': '你好！很高兴为你提供帮助。'})
 
-    messages.append({"role": "user", "content": "给我讲一个年轻人奋斗创业最终取得成功的故事。故事只能有一句话。"})
+    messages.append({
+        'role': 'user',
+        'content': '给我讲一个年轻人奋斗创业最终取得成功的故事。故事只能有一句话。'
+    })
     call_qwen(messages)
-    messages.append(
-        {
-            "role": "assistant",
-            "content": "故事的主人公叫李明，他来自一个普通的家庭，父母都是普通的工人。李明想要成为一名成功的企业家。……",
-        }
-    )
-
-    messages.append({"role": "user", "content": "给这个故事起一个标题"})
+    messages.append({
+        'role':
+        'assistant',
+        'content':
+        '故事的主人公叫李明，他来自一个普通的家庭，父母都是普通的工人。李明想要成为一名成功的企业家。……',
+    })
+
+    messages.append({'role': 'user', 'content': '给这个故事起一个标题'})
     call_qwen(messages)
 
 
 def test_2():
     functions = [
         {
-            "name_for_human": "谷歌搜索",
-            "name_for_model": "google_search",
-            "description_for_model": "谷歌搜索是一个通用搜索引擎，可用于访问互联网、查询百科知识、了解时事新闻等。"
-            + " Format the arguments as a JSON object.",
-            "parameters": [
-                {
-                    "name": "search_query",
-                    "description": "搜索关键词或短语",
-                    "required": True,
-                    "schema": {"type": "string"},
-                }
-            ],
+            'name_for_human':
+            '谷歌搜索',
+            'name_for_model':
+            'google_search',
+            'description_for_model':
+            '谷歌搜索是一个通用搜索引擎，可用于访问互联网、查询百科知识、了解时事新闻等。' +
+            ' Format the arguments as a JSON object.',
+            'parameters': [{
+                'name': 'search_query',
+                'description': '搜索关键词或短语',
+                'required': True,
+                'schema': {
+                    'type': 'string'
+                },
+            }],
         },
         {
-            "name_for_human": "文生图",
-            "name_for_model": "image_gen",
-            "description_for_model": "文生图是一个AI绘画（图像生成）服务，输入文本描述，返回根据文本作画得到的图片的URL。"
-            + " Format the arguments as a JSON object.",
-            "parameters": [
-                {
-                    "name": "prompt",
-                    "description": "英文关键词，描述了希望图像具有什么内容",
-                    "required": True,
-                    "schema": {"type": "string"},
-                }
-            ],
+            'name_for_human':
+            '文生图',
+            'name_for_model':
+            'image_gen',
+            'description_for_model':
+            '文生图是一个AI绘画（图像生成）服务，输入文本描述，返回根据文本作画得到的图片的URL。' +
+            ' Format the arguments as a JSON object.',
+            'parameters': [{
+                'name': 'prompt',
+                'description': '英文关键词，描述了希望图像具有什么内容',
+                'required': True,
+                'schema': {
+                    'type': 'string'
+                },
+            }],
         },
     ]
 
-    messages = [{"role": "user", "content": "你好"}]
+    messages = [{'role': 'user', 'content': '（请不要调用工具）\n\n你好'}]
     call_qwen(messages, functions)
-    messages.append(
-        {"role": "assistant", "content": "你好！很高兴见到你。有什么我可以帮忙的吗？"},
-    )
+    messages.append({
+        'role': 'assistant',
+        'content': '你好！很高兴见到你。有什么我可以帮忙的吗？'
+    }, )
 
-    messages.append({"role": "user", "content": "谁是周杰伦"})
+    messages.append({'role': 'user', 'content': '搜索一下谁是周杰伦'})
     call_qwen(messages, functions)
-    messages.append(
-        {
-            "role": "assistant",
-            "content": "Thought: 我应该使用Google搜索查找相关信息。",
-            "function_call": {
-                "name": "google_search",
-                "arguments": '{"search_query": "周杰伦"}',
-            },
-        }
-    )
-
-    messages.append(
-        {
-            "role": "function",
-            "name": "google_search",
-            "content": "Jay Chou is a Taiwanese singer.",
-        }
-    )
-    call_qwen(messages, functions)
-    messages.append(
-        {
-            "role": "assistant",
-            "content": "周杰伦（Jay Chou）是一位来自台湾的歌手。",
+    messages.append({
+        'role': 'assistant',
+        'content': '我应该使用Google搜索查找相关信息。',
+        'function_call': {
+            'name': 'google_search',
+            'arguments': '{"search_query": "周杰伦"}',
         },
-    )
+    })
 
-    messages.append({"role": "user", "content": "他老婆是谁"})
+    messages.append({
+        'role': 'function',
+        'name': 'google_search',
+        'content': 'Jay Chou is a Taiwanese singer.',
+    })
     call_qwen(messages, functions)
     messages.append(
         {
-            "role": "assistant",
-            "content": "Thought: 我应该使用Google搜索查找相关信息。",
-            "function_call": {
-                "name": "google_search",
-                "arguments": '{"search_query": "周杰伦 老婆"}',
-            },
-        }
-    )
+            'role': 'assistant',
+            'content': '周杰伦（Jay Chou）是一位来自台湾的歌手。',
+        }, )
 
-    messages.append(
-        {"role": "function", "name": "google_search", "content": "Hannah Quinlivan"}
-    )
+    messages.append({'role': 'user', 'content': '搜索一下他老婆是谁'})
     call_qwen(messages, functions)
-    messages.append(
-        {
-            "role": "assistant",
-            "content": "周杰伦的老婆是Hannah Quinlivan。",
+    messages.append({
+        'role': 'assistant',
+        'content': '我应该使用Google搜索查找相关信息。',
+        'function_call': {
+            'name': 'google_search',
+            'arguments': '{"search_query": "周杰伦 老婆"}',
         },
-    )
+    })
 
-    messages.append({"role": "user", "content": "给我画个可爱的小猫吧，最好是黑猫"})
+    messages.append({
+        'role': 'function',
+        'name': 'google_search',
+        'content': 'Hannah Quinlivan'
+    })
     call_qwen(messages, functions)
     messages.append(
         {
-            "role": "assistant",
-            "content": "Thought: 我应该使用文生图API来生成一张可爱的小猫图片。",
-            "function_call": {
-                "name": "image_gen",
-                "arguments": '{"prompt": "cute black cat"}',
-            },
-        }
-    )
+            'role': 'assistant',
+            'content': '周杰伦的老婆是Hannah Quinlivan。',
+        }, )
 
-    messages.append(
-        {
-            "role": "function",
-            "name": "image_gen",
-            "content": '{"image_url": "https://image.pollinations.ai/prompt/cute%20black%20cat"}',
-        }
-    )
+    messages.append({'role': 'user', 'content': '用文生图工具画个可爱的小猫吧，最好是黑猫'})
+    call_qwen(messages, functions)
+    messages.append({
+        'role': 'assistant',
+        'content': '我应该使用文生图API来生成一张可爱的小猫图片。',
+        'function_call': {
+            'name': 'image_gen',
+            'arguments': '{"prompt": "cute black cat"}',
+        },
+    })
+
+    messages.append({
+        'role':
+        'function',
+        'name':
+        'image_gen',
+        'content':
+        '{"image_url": "https://image.pollinations.ai/prompt/cute%20black%20cat"}',
+    })
     call_qwen(messages, functions)
 
 
 def test_3():
-    functions = [
-        {
-            "name": "get_current_weather",
-            "description": "Get the current weather in a given location.",
-            "parameters": {
-                "type": "object",
-                "properties": {
-                    "location": {
-                        "type": "string",
-                        "description": "The city and state, e.g. San Francisco, CA",
-                    },
-                    "unit": {"type": "string", "enum": ["celsius", "fahrenheit"]},
+    functions = [{
+        'name': 'get_current_weather',
+        'description': 'Get the current weather in a given location.',
+        'parameters': {
+            'type': 'object',
+            'properties': {
+                'location': {
+                    'type': 'string',
+                    'description':
+                    'The city and state, e.g. San Francisco, CA',
+                },
+                'unit': {
+                    'type': 'string',
+                    'enum': ['celsius', 'fahrenheit']
                 },
-                "required": ["location"],
             },
-        }
-    ]
-
-    messages = [
-        {
-            "role": "user",
-            # Note: The current version of Qwen-7B-Chat (as of 2023.08) performs okay with Chinese tool-use prompts,
-            # but performs terribly when it comes to English tool-use prompts, due to a mistake in data collecting.
-            "content": "波士顿天气如何？",
-        }
-    ]
+            'required': ['location'],
+        },
+    }]
+
+    messages = [{
+        'role': 'user',
+        # Note: The current version of Qwen-7B-Chat (as of 2023.08) performs okay with Chinese tool-use prompts,
+        # but performs terribly when it comes to English tool-use prompts, due to a mistake in data collecting.
+        'content': '波士顿天气如何？',
+    }]
     call_qwen(messages, functions)
     messages.append(
         {
-            "role": "assistant",
-            "content": None,
-            "function_call": {
-                "name": "get_current_weather",
-                "arguments": '{"location": "Boston, MA"}',
+            'role': 'assistant',
+            'content': None,
+            'function_call': {
+                'name': 'get_current_weather',
+                'arguments': '{"location": "Boston, MA"}',
             },
-        },
-    )
-
-    messages.append(
-        {
-            "role": "function",
-            "name": "get_current_weather",
-            "content": '{"temperature": "22", "unit": "celsius", "description": "Sunny"}',
-        }
-    )
+        }, )
+
+    messages.append({
+        'role':
+        'function',
+        'name':
+        'get_current_weather',
+        'content':
+        '{"temperature": "22", "unit": "celsius", "description": "Sunny"}',
+    })
     call_qwen(messages, functions)
 
 
 def test_4():
+    from langchain.agents import AgentType, initialize_agent, load_tools
     from langchain.chat_models import ChatOpenAI
-    from langchain.agents import load_tools, initialize_agent, AgentType
 
     llm = ChatOpenAI(
-        model_name="Qwen",
-        openai_api_base="http://localhost:8000/v1",
-        openai_api_key="EMPTY",
+        model_name='Qwen',
+        openai_api_base='http://localhost:8000/v1',
+        openai_api_key='EMPTY',
         streaming=False,
     )
-    tools = load_tools(
-        ["arxiv"],
-    )
+    tools = load_tools(['arxiv'], )
     agent_chain = initialize_agent(
         tools,
         llm,
@@ -226,15 +235,15 @@ def test_4():
         verbose=True,
     )
     # TODO: The performance is okay with Chinese prompts, but not so good when it comes to English.
-    agent_chain.run("查一下论文 1605.08386 的信息")
+    agent_chain.run('查一下论文 1605.08386 的信息')
 
 
-if __name__ == "__main__":
-    print("### Test Case 1 - No Function Calling (普通问答、无函数调用) ###")
+if __name__ == '__main__':
+    print('### Test Case 1 - No Function Calling (普通问答、无函数调用) ###')
     test_1()
-    print("### Test Case 2 - Use Qwen-Style Functions (函数调用，千问格式) ###")
+    print('### Test Case 2 - Use Qwen-Style Functions (函数调用，千问格式) ###')
     test_2()
-    print("### Test Case 3 - Use GPT-Style Functions (函数调用，GPT格式) ###")
+    print('### Test Case 3 - Use GPT-Style Functions (函数调用，GPT格式) ###')
     test_3()
-    print("### Test Case 4 - Use LangChain (接入Langchain) ###")
+    print('### Test Case 4 - Use LangChain (接入Langchain) ###')
     test_4()
diff --git a/openai_api.py b/openai_api.py
index e9674bc..fd8e635 100644
--- a/openai_api.py
+++ b/openai_api.py
@@ -1,14 +1,16 @@
-# coding=utf-8
-# Implements API for Qwen-7B in OpenAI's format. (https://platform.openai.com/docs/api-reference/chat)
-# Usage: python openai_api.py
+# Requirement:
+#   pip install "openai<1.0"
+# Usage:
+#   python openai_api.py
 # Visit http://localhost:8000/docs for documents.
 
-import re
+import base64
 import copy
 import json
 import time
 from argparse import ArgumentParser
 from contextlib import asynccontextmanager
+from pprint import pprint
 from typing import Dict, List, Literal, Optional, Union
 
 import torch
@@ -17,20 +19,22 @@
 from fastapi.middleware.cors import CORSMiddleware
 from pydantic import BaseModel, Field
 from sse_starlette.sse import EventSourceResponse
-from transformers import AutoTokenizer, AutoModelForCausalLM
-from transformers.generation import GenerationConfig
 from starlette.middleware.base import BaseHTTPMiddleware
 from starlette.requests import Request
 from starlette.responses import Response
-import base64
+from transformers import AutoModelForCausalLM, AutoTokenizer
+from transformers.generation import GenerationConfig
+
 
 class BasicAuthMiddleware(BaseHTTPMiddleware):
+
     def __init__(self, app, username: str, password: str):
         super().__init__(app)
-        self.required_credentials = base64.b64encode(f"{username}:{password}".encode()).decode()
+        self.required_credentials = base64.b64encode(
+            f'{username}:{password}'.encode()).decode()
 
     async def dispatch(self, request: Request, call_next):
-        authorization: str = request.headers.get("Authorization")
+        authorization: str = request.headers.get('Authorization')
         if authorization:
             try:
                 schema, credentials = authorization.split()
@@ -38,16 +42,18 @@ async def dispatch(self, request: Request, call_next):
                     return await call_next(request)
             except ValueError:
                 pass
-        
+
         headers = {'WWW-Authenticate': 'Basic'}
         return Response(status_code=401, headers=headers)
-    
+
+
 def _gc(forced: bool = False):
     global args
     if args.disable_gc and not forced:
         return
 
     import gc
+
     gc.collect()
     if torch.cuda.is_available():
         torch.cuda.empty_cache()
@@ -63,36 +69,36 @@ async def lifespan(app: FastAPI):  # collects GPU memory
 
 app.add_middleware(
     CORSMiddleware,
-    allow_origins=["*"],
+    allow_origins=['*'],
     allow_credentials=True,
-    allow_methods=["*"],
-    allow_headers=["*"],
+    allow_methods=['*'],
+    allow_headers=['*'],
 )
 
 
 class ModelCard(BaseModel):
     id: str
-    object: str = "model"
+    object: str = 'model'
     created: int = Field(default_factory=lambda: int(time.time()))
-    owned_by: str = "owner"
+    owned_by: str = 'owner'
     root: Optional[str] = None
     parent: Optional[str] = None
     permission: Optional[list] = None
 
 
 class ModelList(BaseModel):
-    object: str = "list"
+    object: str = 'list'
     data: List[ModelCard] = []
 
 
 class ChatMessage(BaseModel):
-    role: Literal["user", "assistant", "system", "function"]
+    role: Literal['user', 'assistant', 'system', 'function']
     content: Optional[str]
     function_call: Optional[Dict] = None
 
 
 class DeltaMessage(BaseModel):
-    role: Optional[Literal["user", "assistant", "system"]] = None
+    role: Optional[Literal['user', 'assistant', 'system']] = None
     content: Optional[str] = None
 
 
@@ -102,6 +108,7 @@ class ChatCompletionRequest(BaseModel):
     functions: Optional[List[Dict]] = None
     temperature: Optional[float] = None
     top_p: Optional[float] = None
+    top_k: Optional[int] = None
     max_length: Optional[int] = None
     stream: Optional[bool] = False
     stop: Optional[List[str]] = None
@@ -109,29 +116,28 @@ class ChatCompletionRequest(BaseModel):
 
 class ChatCompletionResponseChoice(BaseModel):
     index: int
-    message: ChatMessage
-    finish_reason: Literal["stop", "length", "function_call"]
+    message: Union[ChatMessage]
+    finish_reason: Literal['stop', 'length', 'function_call']
 
 
 class ChatCompletionResponseStreamChoice(BaseModel):
     index: int
     delta: DeltaMessage
-    finish_reason: Optional[Literal["stop", "length"]]
+    finish_reason: Optional[Literal['stop', 'length']]
 
 
 class ChatCompletionResponse(BaseModel):
     model: str
-    object: Literal["chat.completion", "chat.completion.chunk"]
-    choices: List[
-        Union[ChatCompletionResponseChoice, ChatCompletionResponseStreamChoice]
-    ]
+    object: Literal['chat.completion', 'chat.completion.chunk']
+    choices: List[Union[ChatCompletionResponseChoice,
+                        ChatCompletionResponseStreamChoice]]
     created: Optional[int] = Field(default_factory=lambda: int(time.time()))
 
 
-@app.get("/v1/models", response_model=ModelList)
+@app.get('/v1/models', response_model=ModelList)
 async def list_models():
     global model_args
-    model_card = ModelCard(id="gpt-3.5-turbo")
+    model_card = ModelCard(id='gpt-3.5-turbo')
     return ModelList(data=[model_card])
 
 
@@ -141,7 +147,7 @@ def add_extra_stop_words(stop_words):
         _stop_words = []
         _stop_words.extend(stop_words)
         for x in stop_words:
-            s = x.lstrip("\n")
+            s = x.lstrip('\n')
             if s and (s not in _stop_words):
                 _stop_words.append(s)
         return _stop_words
@@ -157,7 +163,10 @@ def trim_stop_words(response, stop_words):
     return response
 
 
-TOOL_DESC = """{name_for_model}: Call this tool to interact with the {name_for_human} API. What is the {name_for_human} API useful for? {description_for_model} Parameters: {parameters}"""
+TOOL_DESC = (
+    '{name_for_model}: Call this tool to interact with the {name_for_human} API.'
+    ' What is the {name_for_human} API useful for? {description_for_model} Parameters: {parameters}'
+)
 
 REACT_INSTRUCTION = """Answer the following questions as best you can. You have access to the following APIs:
 
@@ -179,37 +188,28 @@ def trim_stop_words(response, stop_words):
 _TEXT_COMPLETION_CMD = object()
 
 
-#
-# Temporarily, the system role does not work as expected.
-# We advise that you write the setups for role-play in your query,
-# i.e., use the user role instead of the system role.
-#
-# TODO: Use real system role when the model is ready.
-#
 def parse_messages(messages, functions):
-    if all(m.role != "user" for m in messages):
+    if all(m.role != 'user' for m in messages):
         raise HTTPException(
             status_code=400,
-            detail=f"Invalid request: Expecting at least one user message.",
+            detail='Invalid request: Expecting at least one user message.',
         )
 
     messages = copy.deepcopy(messages)
-    default_system = "You are a helpful assistant."
-    system = ""
-    if messages[0].role == "system":
-        system = messages.pop(0).content.lstrip("\n").rstrip()
-        if system == default_system:
-            system = ""
+    if messages[0].role == 'system':
+        system = messages.pop(0).content.lstrip('\n').rstrip()
+    else:
+        system = 'You are a helpful assistant.'
 
     if functions:
         tools_text = []
         tools_name_text = []
         for func_info in functions:
-            name = func_info.get("name", "")
-            name_m = func_info.get("name_for_model", name)
-            name_h = func_info.get("name_for_human", name)
-            desc = func_info.get("description", "")
-            desc_m = func_info.get("description_for_model", desc)
+            name = func_info.get('name', '')
+            name_m = func_info.get('name_for_model', name)
+            name_h = func_info.get('name_for_human', name)
+            desc = func_info.get('description', '')
+            desc_m = func_info.get('description_for_model', desc)
             tool = TOOL_DESC.format(
                 name_for_model=name_m,
                 name_for_human=name_h,
@@ -217,150 +217,152 @@ def parse_messages(messages, functions):
                 #   "Format the arguments as a JSON object."
                 #   "Enclose the code within triple backticks (`) at the beginning and end of the code."
                 description_for_model=desc_m,
-                parameters=json.dumps(func_info["parameters"], ensure_ascii=False),
+                parameters=json.dumps(func_info['parameters'],
+                                      ensure_ascii=False),
             )
             tools_text.append(tool)
             tools_name_text.append(name_m)
-        tools_text = "\n\n".join(tools_text)
-        tools_name_text = ", ".join(tools_name_text)
-        system += "\n\n" + REACT_INSTRUCTION.format(
+        tools_text = '\n\n'.join(tools_text)
+        tools_name_text = ', '.join(tools_name_text)
+        instruction = (REACT_INSTRUCTION.format(
             tools_text=tools_text,
             tools_name_text=tools_name_text,
-        )
-        system = system.lstrip("\n").rstrip()
-
-    dummy_thought = {
-        "en": "\nThought: I now know the final answer.\nFinal answer: ",
-        "zh": "\nThought: 我会作答了。\nFinal answer: ",
-    }
+        ).lstrip('\n').rstrip())
+    else:
+        instruction = ''
 
-    _messages = messages
+    messages_with_fncall = messages
     messages = []
-    for m_idx, m in enumerate(_messages):
+    for m_idx, m in enumerate(messages_with_fncall):
         role, content, func_call = m.role, m.content, m.function_call
-        if content:
-            content = content.lstrip("\n").rstrip()
-        if role == "function":
-            if (len(messages) == 0) or (messages[-1].role != "assistant"):
+        content = content or ''
+        content = content.lstrip('\n').rstrip()
+        if role == 'function':
+            if (len(messages) == 0) or (messages[-1].role != 'assistant'):
                 raise HTTPException(
                     status_code=400,
-                    detail=f"Invalid request: Expecting role assistant before role function.",
+                    detail=
+                    'Invalid request: Expecting role assistant before role function.',
                 )
-            messages[-1].content += f"\nObservation: {content}"
-            if m_idx == len(_messages) - 1:
-                messages[-1].content += "\nThought:"
-        elif role == "assistant":
+            messages[-1].content += f'\nObservation: {content}'
+            if m_idx == len(messages_with_fncall) - 1:
+                # add a prefix for text completion
+                messages[-1].content += '\nThought:'
+        elif role == 'assistant':
             if len(messages) == 0:
                 raise HTTPException(
                     status_code=400,
-                    detail=f"Invalid request: Expecting role user before role assistant.",
+                    detail=
+                    'Invalid request: Expecting role user before role assistant.',
                 )
-            last_msg = messages[-1].content
-            last_msg_has_zh = len(re.findall(r"[\u4e00-\u9fff]+", last_msg)) > 0
             if func_call is None:
                 if functions:
-                    content = dummy_thought["zh" if last_msg_has_zh else "en"] + content
+                    content = f'Thought: I now know the final answer.\nFinal Answer: {content}'
             else:
-                f_name, f_args = func_call["name"], func_call["arguments"]
-                if not content:
-                    if last_msg_has_zh:
-                        content = f"Thought: 我可以使用 {f_name} API。"
-                    else:
-                        content = f"Thought: I can use {f_name}."
-                content = f"\n{content}\nAction: {f_name}\nAction Input: {f_args}"
-            if messages[-1].role == "user":
+                f_name, f_args = func_call['name'], func_call['arguments']
+                if not content.startswith('Thought:'):
+                    content = f'Thought: {content}'
+                content = f'{content}\nAction: {f_name}\nAction Input: {f_args}'
+            if messages[-1].role == 'user':
                 messages.append(
-                    ChatMessage(role="assistant", content=content.lstrip("\n").rstrip())
-                )
+                    ChatMessage(role='assistant',
+                                content=content.lstrip('\n').rstrip()))
             else:
-                messages[-1].content += content
-        elif role == "user":
+                messages[-1].content += '\n' + content
+        elif role == 'user':
             messages.append(
-                ChatMessage(role="user", content=content.lstrip("\n").rstrip())
-            )
+                ChatMessage(role='user',
+                            content=content.lstrip('\n').rstrip()))
         else:
             raise HTTPException(
-                status_code=400, detail=f"Invalid request: Incorrect role {role}."
-            )
+                status_code=400,
+                detail=f'Invalid request: Incorrect role {role}.')
 
     query = _TEXT_COMPLETION_CMD
-    if messages[-1].role == "user":
+    if messages[-1].role == 'user':
         query = messages[-1].content
         messages = messages[:-1]
 
     if len(messages) % 2 != 0:
-        raise HTTPException(status_code=400, detail="Invalid request")
+        raise HTTPException(status_code=400, detail='Invalid request')
 
     history = []  # [(Q1, A1), (Q2, A2), ..., (Q_last_turn, A_last_turn)]
     for i in range(0, len(messages), 2):
-        if messages[i].role == "user" and messages[i + 1].role == "assistant":
-            usr_msg = messages[i].content.lstrip("\n").rstrip()
-            bot_msg = messages[i + 1].content.lstrip("\n").rstrip()
-            if system and (i == len(messages) - 2):
-                usr_msg = f"{system}\n\nQuestion: {usr_msg}"
-                system = ""
-            for t in dummy_thought.values():
-                t = t.lstrip("\n")
-                if bot_msg.startswith(t) and ("\nAction: " in bot_msg):
-                    bot_msg = bot_msg[len(t) :]
+        if messages[i].role == 'user' and messages[i + 1].role == 'assistant':
+            usr_msg = messages[i].content.lstrip('\n').rstrip()
+            bot_msg = messages[i + 1].content.lstrip('\n').rstrip()
+            if instruction and (i == len(messages) - 2):
+                usr_msg = f'{instruction}\n\nQuestion: {usr_msg}'
+                instruction = ''
             history.append([usr_msg, bot_msg])
         else:
             raise HTTPException(
                 status_code=400,
-                detail="Invalid request: Expecting exactly one user (or function) role before every assistant role.",
+                detail=
+                'Invalid request: Expecting exactly one user (or function) role before every assistant role.',
             )
-    if system:
+    if instruction:
         assert query is not _TEXT_COMPLETION_CMD
-        query = f"{system}\n\nQuestion: {query}"
-    return query, history
+        query = f'{instruction}\n\nQuestion: {query}'
+    return query, history, system
 
 
 def parse_response(response):
-    func_name, func_args = "", ""
-    i = response.rfind("\nAction:")
-    j = response.rfind("\nAction Input:")
-    k = response.rfind("\nObservation:")
+    func_name, func_args = '', ''
+    i = response.find('\nAction:')
+    j = response.find('\nAction Input:')
+    k = response.find('\nObservation:')
     if 0 <= i < j:  # If the text has `Action` and `Action input`,
         if k < j:  # but does not contain `Observation`,
             # then it is likely that `Observation` is omitted by the LLM,
             # because the output text may have discarded the stop word.
-            response = response.rstrip() + "\nObservation:"  # Add it back.
-        k = response.rfind("\nObservation:")
-        func_name = response[i + len("\nAction:") : j].strip()
-        func_args = response[j + len("\nAction Input:") : k].strip()
+            response = response.rstrip() + '\nObservation:'  # Add it back.
+        k = response.find('\nObservation:')
+        func_name = response[i + len('\nAction:'):j].strip()
+        func_args = response[j + len('\nAction Input:'):k].strip()
+
     if func_name:
+        response = response[:i]
+        t = response.find('Thought: ')
+        if t >= 0:
+            response = response[t + len('Thought: '):]
+        response = response.strip()
         choice_data = ChatCompletionResponseChoice(
             index=0,
             message=ChatMessage(
-                role="assistant",
-                content=response[:i],
-                function_call={"name": func_name, "arguments": func_args},
+                role='assistant',
+                content=response,
+                function_call={
+                    'name': func_name,
+                    'arguments': func_args
+                },
             ),
-            finish_reason="function_call",
+            finish_reason='function_call',
         )
         return choice_data
-    z = response.rfind("\nFinal Answer: ")
+
+    z = response.rfind('\nFinal Answer: ')
     if z >= 0:
-        response = response[z + len("\nFinal Answer: ") :]
+        response = response[z + len('\nFinal Answer: '):]
     choice_data = ChatCompletionResponseChoice(
         index=0,
-        message=ChatMessage(role="assistant", content=response),
-        finish_reason="stop",
+        message=ChatMessage(role='assistant', content=response),
+        finish_reason='stop',
     )
     return choice_data
 
 
 # completion mode, not chat mode
-def text_complete_last_message(history, stop_words_ids, gen_kwargs):
-    im_start = "<|im_start|>"
-    im_end = "<|im_end|>"
-    prompt = f"{im_start}system\nYou are a helpful assistant.{im_end}"
+def text_complete_last_message(history, stop_words_ids, gen_kwargs, system):
+    im_start = '<|im_start|>'
+    im_end = '<|im_end|>'
+    prompt = f'{im_start}system\n{system}{im_end}'
     for i, (query, response) in enumerate(history):
-        query = query.lstrip("\n").rstrip()
-        response = response.lstrip("\n").rstrip()
-        prompt += f"\n{im_start}user\n{query}{im_end}"
-        prompt += f"\n{im_start}assistant\n{response}{im_end}"
-    prompt = prompt[: -len(im_end)]
+        query = query.lstrip('\n').rstrip()
+        response = response.lstrip('\n').rstrip()
+        prompt += f'\n{im_start}user\n{query}{im_end}'
+        prompt += f'\n{im_start}assistant\n{response}{im_end}'
+    prompt = prompt[:-len(im_end)]
 
     _stop_words_ids = [tokenizer.encode(im_end)]
     if stop_words_ids:
@@ -369,20 +371,24 @@ def text_complete_last_message(history, stop_words_ids, gen_kwargs):
     stop_words_ids = _stop_words_ids
 
     input_ids = torch.tensor([tokenizer.encode(prompt)]).to(model.device)
-    output = model.generate(input_ids, stop_words_ids=stop_words_ids, **gen_kwargs).tolist()[0]
-    output = tokenizer.decode(output, errors="ignore")
+    output = model.generate(input_ids,
+                            stop_words_ids=stop_words_ids,
+                            **gen_kwargs).tolist()[0]
+    output = tokenizer.decode(output, errors='ignore')
     assert output.startswith(prompt)
-    output = output[len(prompt) :]
-    output = trim_stop_words(output, ["<|endoftext|>", im_end])
-    print(f"<completion>\n{prompt}\n<!-- *** -->\n{output}\n</completion>")
+    output = output[len(prompt):]
+    output = trim_stop_words(output, ['<|endoftext|>', im_end])
+    print(f'<completion>\n{prompt}\n<!-- *** -->\n{output}\n</completion>')
     return output
 
 
-@app.post("/v1/chat/completions", response_model=ChatCompletionResponse)
+@app.post('/v1/chat/completions', response_model=ChatCompletionResponse)
 async def create_chat_completion(request: ChatCompletionRequest):
     global model, tokenizer
 
     gen_kwargs = {}
+    if request.top_k is not None:
+        gen_kwargs['top_k'] = request.top_k
     if request.temperature is not None:
         if request.temperature < 0.01:
             gen_kwargs['top_k'] = 1  # greedy decoding
@@ -395,32 +401,46 @@ async def create_chat_completion(request: ChatCompletionRequest):
     stop_words = add_extra_stop_words(request.stop)
     if request.functions:
         stop_words = stop_words or []
-        if "Observation:" not in stop_words:
-            stop_words.append("Observation:")
+        if 'Observation:' not in stop_words:
+            stop_words.append('Observation:')
 
-    query, history = parse_messages(request.messages, request.functions)
+    query, history, system = parse_messages(request.messages,
+                                            request.functions)
 
     if request.stream:
         if request.functions:
             raise HTTPException(
                 status_code=400,
-                detail="Invalid request: Function calling is not yet implemented for stream mode.",
+                detail=
+                'Invalid request: Function calling is not yet implemented for stream mode.',
             )
-        generate = predict(query, history, request.model, stop_words, gen_kwargs)
-        return EventSourceResponse(generate, media_type="text/event-stream")
-
-    stop_words_ids = [tokenizer.encode(s) for s in stop_words] if stop_words else None
+        generate = predict(query,
+                           history,
+                           request.model,
+                           stop_words,
+                           gen_kwargs,
+                           system=system)
+        return EventSourceResponse(generate, media_type='text/event-stream')
+
+    stop_words_ids = [tokenizer.encode(s)
+                      for s in stop_words] if stop_words else None
     if query is _TEXT_COMPLETION_CMD:
-        response = text_complete_last_message(history, stop_words_ids=stop_words_ids, gen_kwargs=gen_kwargs)
+        response = text_complete_last_message(history,
+                                              stop_words_ids=stop_words_ids,
+                                              gen_kwargs=gen_kwargs,
+                                              system=system)
     else:
         response, _ = model.chat(
             tokenizer,
             query,
             history=history,
+            system=system,
             stop_words_ids=stop_words_ids,
-            **gen_kwargs
+            **gen_kwargs,
         )
-        print(f"<chat>\n{history}\n{query}\n<!-- *** -->\n{response}\n</chat>")
+        print('<chat>')
+        pprint(history, indent=2)
+        print(f'{query}\n<!-- *** -->\n{response}\n</chat>')
     _gc()
 
     response = trim_stop_words(response, stop_words)
@@ -429,12 +449,12 @@ async def create_chat_completion(request: ChatCompletionRequest):
     else:
         choice_data = ChatCompletionResponseChoice(
             index=0,
-            message=ChatMessage(role="assistant", content=response),
-            finish_reason="stop",
+            message=ChatMessage(role='assistant', content=response),
+            finish_reason='stop',
         )
-    return ChatCompletionResponse(
-        model=request.model, choices=[choice_data], object="chat.completion"
-    )
+    return ChatCompletionResponse(model=request.model,
+                                  choices=[choice_data],
+                                  object='chat.completion')
 
 
 def _dump_json(data: BaseModel, *args, **kwargs) -> str:
@@ -445,28 +465,37 @@ def _dump_json(data: BaseModel, *args, **kwargs) -> str:
 
 
 async def predict(
-    query: str, history: List[List[str]], model_id: str, stop_words: List[str], gen_kwargs: Dict,
+    query: str,
+    history: List[List[str]],
+    model_id: str,
+    stop_words: List[str],
+    gen_kwargs: Dict,
+    system: str,
 ):
     global model, tokenizer
     choice_data = ChatCompletionResponseStreamChoice(
-        index=0, delta=DeltaMessage(role="assistant"), finish_reason=None
-    )
-    chunk = ChatCompletionResponse(
-        model=model_id, choices=[choice_data], object="chat.completion.chunk"
-    )
-    yield "{}".format(_dump_json(chunk, exclude_unset=True))
+        index=0, delta=DeltaMessage(role='assistant'), finish_reason=None)
+    chunk = ChatCompletionResponse(model=model_id,
+                                   choices=[choice_data],
+                                   object='chat.completion.chunk')
+    yield '{}'.format(_dump_json(chunk, exclude_unset=True))
 
     current_length = 0
-    stop_words_ids = [tokenizer.encode(s) for s in stop_words] if stop_words else None
+    stop_words_ids = [tokenizer.encode(s)
+                      for s in stop_words] if stop_words else None
     if stop_words:
         # TODO: It's a little bit tricky to trim stop words in the stream mode.
         raise HTTPException(
             status_code=400,
-            detail="Invalid request: custom stop words are not yet supported for stream mode.",
+            detail=
+            'Invalid request: custom stop words are not yet supported for stream mode.',
         )
-    response_generator = model.chat_stream(
-        tokenizer, query, history=history, stop_words_ids=stop_words_ids, **gen_kwargs
-    )
+    response_generator = model.chat_stream(tokenizer,
+                                           query,
+                                           history=history,
+                                           stop_words_ids=stop_words_ids,
+                                           system=system,
+                                           **gen_kwargs)
     for new_response in response_generator:
         if len(new_response) == current_length:
             continue
@@ -475,21 +504,20 @@ async def predict(
         current_length = len(new_response)
 
         choice_data = ChatCompletionResponseStreamChoice(
-            index=0, delta=DeltaMessage(content=new_text), finish_reason=None
-        )
-        chunk = ChatCompletionResponse(
-            model=model_id, choices=[choice_data], object="chat.completion.chunk"
-        )
-        yield "{}".format(_dump_json(chunk, exclude_unset=True))
-
-    choice_data = ChatCompletionResponseStreamChoice(
-        index=0, delta=DeltaMessage(), finish_reason="stop"
-    )
-    chunk = ChatCompletionResponse(
-        model=model_id, choices=[choice_data], object="chat.completion.chunk"
-    )
-    yield "{}".format(_dump_json(chunk, exclude_unset=True))
-    yield "[DONE]"
+            index=0, delta=DeltaMessage(content=new_text), finish_reason=None)
+        chunk = ChatCompletionResponse(model=model_id,
+                                       choices=[choice_data],
+                                       object='chat.completion.chunk')
+        yield '{}'.format(_dump_json(chunk, exclude_unset=True))
+
+    choice_data = ChatCompletionResponseStreamChoice(index=0,
+                                                     delta=DeltaMessage(),
+                                                     finish_reason='stop')
+    chunk = ChatCompletionResponse(model=model_id,
+                                   choices=[choice_data],
+                                   object='chat.completion.chunk')
+    yield '{}'.format(_dump_json(chunk, exclude_unset=True))
+    yield '[DONE]'
 
     _gc()
 
@@ -497,36 +525,39 @@ async def predict(
 def _get_args():
     parser = ArgumentParser()
     parser.add_argument(
-        "-c",
-        "--checkpoint-path",
+        '-c',
+        '--checkpoint-path',
         type=str,
-        default="Qwen/Qwen-7B-Chat",
-        help="Checkpoint name or path, default to %(default)r",
+        default='Qwen/Qwen-7B-Chat',
+        help='Checkpoint name or path, default to %(default)r',
     )
+    parser.add_argument('--api-auth', help='API authentication credentials')
+    parser.add_argument('--cpu-only',
+                        action='store_true',
+                        help='Run demo with CPU only')
+    parser.add_argument('--server-port',
+                        type=int,
+                        default=8000,
+                        help='Demo server port.')
     parser.add_argument(
-        "--api-auth", help="API authentication credentials"
-    )
-    parser.add_argument(
-        "--cpu-only", action="store_true", help="Run demo with CPU only"
-    )
-    parser.add_argument(
-        "--server-port", type=int, default=8000, help="Demo server port."
+        '--server-name',
+        type=str,
+        default='127.0.0.1',
+        help=
+        'Demo server name. Default: 127.0.0.1, which is only visible from the local computer.'
+        ' If you want other computers to access your server, use 0.0.0.0 instead.',
     )
     parser.add_argument(
-        "--server-name",
-        type=str,
-        default="127.0.0.1",
-        help="Demo server name. Default: 127.0.0.1, which is only visible from the local computer."
-        " If you want other computers to access your server, use 0.0.0.0 instead.",
+        '--disable-gc',
+        action='store_true',
+        help='Disable GC after each response generated.',
     )
-    parser.add_argument("--disable-gc", action="store_true",
-                        help="Disable GC after each response generated.")
 
     args = parser.parse_args()
     return args
 
 
-if __name__ == "__main__":
+if __name__ == '__main__':
     args = _get_args()
 
     tokenizer = AutoTokenizer.from_pretrained(
@@ -536,14 +567,14 @@ def _get_args():
     )
 
     if args.api_auth:
-        app.add_middleware(
-            BasicAuthMiddleware, username=args.api_auth.split(":")[0], password=args.api_auth.split(":")[1]
-        )
+        app.add_middleware(BasicAuthMiddleware,
+                           username=args.api_auth.split(':')[0],
+                           password=args.api_auth.split(':')[1])
 
     if args.cpu_only:
-        device_map = "cpu"
+        device_map = 'cpu'
     else:
-        device_map = "auto"
+        device_map = 'auto'
 
     model = AutoModelForCausalLM.from_pretrained(
         args.checkpoint_path,