[BUG]ET_DataExtension requires a columns list, even if there is no intent to add columns

[cheitzig]

Describe the bug
Using the ET_DataExtension() class to (for example) rename a data extension doesn't work unless you create columns attribute with an empty list.
To Reproduce
Specifically, this code, from the documentation, here, fails.

import ET_Client
myClient = ET_Client.ET_Client()
dataextension = ET_Client.ET_DataExtension()
dataextension.auth_stub = myClient
dataextension.props = {"CustomerKey" : "151515151", "Name": "SDK Example, now Updated!"}
results = dataextension.patch()
print results

It works though, if you add this line someplace before the call to patch()
dataextension.columns = []

Expected behavior
A clear and concise description of what you expected to happen.

Screenshots
If applicable, add screenshots to help explain your problem.

Code snippet

import ET_Client
myClient = ET_Client.ET_Client()
dataextension = ET_Client.ET_DataExtension()
dataextension.auth_stub = myClient
dataextension.props = {"CustomerKey" : "151515151", "Name": "SDK Example, now Updated!"}
results = dataextension.patch()
print results

Environment

• SDK Version 1.3.0
• Python version 3.9.1

The bug has the severity

• Critical: The defect affects critical functionality or critical data. It does not have a workaround.
• Major: The defect affects major functionality or major data. It has a workaround but is not obvious and is difficult.
• Minor: The defect affects minor functionality or non-critical data. It has an easy workaround.
• Trivial: The defect does not affect functionality or data. It does not even need a workaround. It does not impact productivity or efficiency. It is merely an inconvenience.

Additional context
Possible fix: line 176 and line 186 should have an if around them. Maybe all of 171-188 should have that if because (maybe) the only purpose of that code is to add columns for either a single or multiple DE's, but I'm not clear on that.

[cvvishalkumar]

Thank you so much for the work-around! I was able to resolve the below error by using blank columns. Thanks.

Traceback (most recent call last): File "d:\vishal\Python\Vishal_LearnPython\UpdateDE.py", line 11, in <module> results = request.patch() File "D:\vishal\Python\lib\site-packages\FuelSDK\objects.py", line 196, in patch for key in self.columns: TypeError: 'NoneType' object is not iterable