来自traceback import format_exception_only ImportError：无法导入名称'format_exception_only'

Question

我收到标题中提到的错误。从命令提示符调用代码时。还会在代码后附加错误路径。我使用的是python 3.5.3版本。导入NLTK lib时发现错误。

命令：

Python Maintest.py

代码：

# file name Maintest.py
import sys
#import nltk #on commenting the code runs fine  

an_error = IndexError('tuple index out of range')
print(an_error)

def demorun():
    print("Demo code called")

def main(argv):
    print("Run the demo ")
    demorun()

if __name__ == '__main__':
    main(sys.argv)

错误：

C:\samat\Sample\Python\Todo>python C:\samat\Sample\Python\Todo\MainTest.py

Traceback (most recent call last):
  File "C:\samat\Sample\Python\Todo\MainTest.py", line 3, in <module>


import nltk
  File "C:\Users\winduser\AppData\Local\Programs\Python\Python35\lib\site-packages\nltk\__init__.py", line 89, in <module>


from nltk.internals import config_java
  File "C:\Users\winduser\AppData\Local\Programs\Python\Python35\lib\site-packages\nltk\internals.py", line 11, in <module>


import subprocess
  File "C:\Users\winduser\AppData\Local\Programs\Python\Python35\Lib\subprocess.py", line 117, in <module>


import threading
  File "C:\Users\winduser\AppData\Local\Programs\Python\Python35\Lib\threading.py", line 7, in <module>


from traceback import format_exc as _format_exc
  File "C:\Users\winduser\AppData\Local\Programs\Python\Python35\Lib\traceback.py", line 5, in <module>


import linecache
  File "C:\Users\winduser\AppData\Local\Programs\Python\Python35\Lib\linecache.py", line 11, in <module>


import tokenize
  File "C:\samat\Sample\Python\Todo\tokenize.py", line 2, in <module>


from nltk.tokenize import sent_tokenize,word_tokenize
  File "C:\Users\winduser\AppData\Local\Programs\Python\Python35\lib\site-packages\nltk\tokenize\__init__.py", line 64, in <module>


from nltk.tokenize.mwe      import MWETokenizer
  File "C:\Users\winduser\AppData\Local\Programs\Python\Python35\lib\site-packages\nltk\tokenize\mwe.py", line 31, in <module>


 from nltk.util import Trie
  File "C:\Users\winduser\AppData\Local\Programs\Python\Python35\lib\site-packages\nltk\util.py", line 13, in <module>


import pydoc
  File "C:\Users\winduser\AppData\Local\Programs\Python\Python35\Lib\pydoc.py", line 72, in <module>


from traceback import format_exception_only

 importError: cannot import name 'format_exception_only'