Fails to load tableStyleElement without a dxfId
*Created originally on Bitbucket by [kound (Carli)](https://bitbucket.org/%7B4c69b10f-5001-445e-a563-b7e83e9bbb54%7D/)* Excel 2010 creates a TableStyleElement with no dxfId Elment but an size element (see example attached), if you configure "Stripe Size" to 2 (or more) It will only contain a size tag: <tableStyleElement type="secondRowStripe" size="2"/> Openpyxl fails to load this file as it can't convert the not existing dxfId ("None") to int. Expected behavior: warn about the not existing dxfId element but still load the file. Tracelog: File "C:\ProgramData\Anaconda3\lib\site-packages\spyder\utils\site\sitecustomize.py", line 880, in runfile execfile(filename, namespace) File "C:\ProgramData\Anaconda3\lib\site-packages\spyder\utils\site\sitecustomize.py", line 102, in execfile exec(compile(f.read(), filename, 'exec'), namespace) File "C:/Users/00068549/Documents/Pyhton/openpyxl_test.py", line 14, in <module> with xl.load_workbook(Testfile,read_only=True,data_only=True) as wb: File "C:\ProgramData\Anaconda3\lib\site-packages\openpyxl\reader\excel.py", line 221, in load_workbook apply_stylesheet(archive, wb) # bind styles to workbook File "C:\ProgramData\Anaconda3\lib\site-packages\openpyxl\styles\stylesheet.py", line 183, in apply_stylesheet stylesheet = Stylesheet.from_tree(node) File "C:\ProgramData\Anaconda3\lib\site-packages\openpyxl\styles\stylesheet.py", line 99, in from_tree return super(Stylesheet, cls).from_tree(node) File "C:\ProgramData\Anaconda3\lib\site-packages\openpyxl\descriptors\serialisable.py", line 80, in from_tree obj = desc.expected_type.from_tree(el) File "C:\ProgramData\Anaconda3\lib\site-packages\openpyxl\descriptors\serialisable.py", line 80, in from_tree obj = desc.expected_type.from_tree(el) File "C:\ProgramData\Anaconda3\lib\site-packages\openpyxl\descriptors\serialisable.py", line 80, in from_tree obj = desc.expected_type.from_tree(el) File "C:\ProgramData\Anaconda3\lib\site-packages\openpyxl\descriptors\serialisable.py", line 93, in from_tree return cls(**attrib) File "C:\ProgramData\Anaconda3\lib\site-packages\openpyxl\styles\table.py", line 37, in __init__ self.dxfId = dxfId File "C:\ProgramData\Anaconda3\lib\site-packages\openpyxl\descriptors\base.py", line 69, in __set__ value = _convert(self.expected_type, value) File "C:\ProgramData\Anaconda3\lib\site-packages\openpyxl\descriptors\base.py", line 59, in _convert raise TypeError('expected ' + str(expected_type)) TypeError: expected <class 'int'> *Attachments:* [minimal.xlsx](/uploads/9773eb1530c1eded58bde3eaceb67f2a/minimal.xlsx)
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