generating metadata error

[mittalparul]

Hello,
I have downloaded Landsat 7 scene from Earth Explorer.
but when I'm going to run python script
python usgs_ls_ard_prepare.py /datacube/original_data/LE07_L1TP_231067
_20150802_20161022_01_T1

it is generating the following error:

2018-09-17 08:34:11,843 INFO Processing /datacube/original_data/LE07_L1TP_231067_20150802_20161022_01_T1
Traceback (most recent call last):
  File "usgs_ls_ard_prepare.py", line 320, in <module>
    main()
  File "/home/parul/Datacube/datacube_env/lib/python3.5/site-packages/click-6.7-py3.5.egg/click/core.py", line 722, in __call__
    return self.main(*args, **kwargs)
  File "/home/parul/Datacube/datacube_env/lib/python3.5/site-packages/click-6.7-py3.5.egg/click/core.py", line 697, in main
    rv = self.invoke(ctx)
  File "/home/parul/Datacube/datacube_env/lib/python3.5/site-packages/click-6.7-py3.5.egg/click/core.py", line 895, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "/home/parul/Datacube/datacube_env/lib/python3.5/site-packages/click-6.7-py3.5.egg/click/core.py", line 535, in invoke
    return callback(*args, **kwargs)
  File "usgs_ls_ard_prepare.py", line 310, in main
    documents = prepare_datasets(path)
  File "usgs_ls_ard_prepare.py", line 286, in prepare_datasets
    r"(?P<collection_category>RT|T1|T2)"), nbar_path.stem).groupdict()
AttributeError: 'NoneType' object has no attribute 'groupdict'

Please suggest me a solution. Thanks in advance.