안녕하세요 pycham툴에서 https://github.com/mete0r/pyhwp.git master의 소스를 clone해서 src의 hwp5proc.py를 run했는데

C:\Users\kyshi\AppData\Local\Programs\Python\Python37\python.exe "C:\Program Files\JetBrains\PyCharm Community Edition 2020.1.2\plugins\python-ce\helpers\pydev\pydevconsole.py" --mode=client --port=63123
import sys; print('Python %s on %s' % (sys.version, sys.platform))
sys.path.extend(['C:\\Projects\\pyhwp', 'C:/Projects/pyhwp'])
PyDev console: starting.
Python 3.7.7 (tags/v3.7.7:d7c567b08f, Mar 10 2020, 10:41:24) [MSC v.1900 64 bit (AMD64)] on win32
runfile('C:/Projects/pyhwp/src/hwp5/hwp5proc.py', wdir='C:/Projects/pyhwp/src/hwp5')
Traceback (most recent call last):
  File "<input>", line 1, in <module>
  File "C:\Program Files\JetBrains\PyCharm Community Edition 2020.1.2\plugins\python-ce\helpers\pydev\_pydev_bundle\pydev_umd.py", line 197, in runfile
    pydev_imports.execfile(filename, global_vars, local_vars)  # execute the script
  File "C:\Program Files\JetBrains\PyCharm Community Edition 2020.1.2\plugins\python-ce\helpers\pydev\_pydev_imps\_pydev_execfile.py", line 18, in execfile
    exec(compile(contents+"\n", file, 'exec'), glob, loc)
  File "C:/Projects/pyhwp/src/hwp5/hwp5proc.py", line 28, in <module>
    from . import __version__
  File "C:\Program Files\JetBrains\PyCharm Community Edition 2020.1.2\plugins\python-ce\helpers\pydev\_pydev_bundle\pydev_import_hook.py", line 21, in do_import
    module = self._system_import(name, *args, **kwargs)
ImportError: attempted relative import with no known parent package

왜 이런 오류가 나는걸까요? 구글링을 찾아봐도 별다른 대안이 없어서 답답한 마음에 문의 드립니다. 꼭 이놈을 수정해야 하는데 ㅠㅠ 힘드네요 고맙습니다.