AttributeError: 'module' object has no attribute 'letters'

[black_13]

what does this error mean?
i am trying to use mark hammonds win32 package.

Traceback (most recent call last):
  File "aui2.py", line 11, in <module>
    import win32com.client
  File "C:\Python25\lib\site-packages\win32com\client\__init__.py",
line 12, in <module>
    import dynamic, gencache, pythoncom
  File "C:\Python25\Lib\site-packages\win32com\client\dynamic.py",
line 24, in <module>
    import build
  File "C:\Python25\lib\site-packages\win32com\client\build.py", line
507, in <module>
    valid_identifier_chars = string.letters + string.digits + "_"
AttributeError: 'module' object has no attribute 'letters'

thanks
black_13