TypeError: FlexUnlimited.register_attestation

[ghost]

Traceback (most recent call last):
File "/home/ubuntu/Desktop/AmazonFlexUnlimited420-master/app.py", line 15, in
flexUnlimited.run()
File "/home/ubuntu/Desktop/AmazonFlexUnlimited420-master/lib/FlexUnlimited.py", line 623, in run
self.__processOffer(offerResponseObject)
File "/home/ubuntu/Desktop/AmazonFlexUnlimited420-master/lib/FlexUnlimited.py", line 568, in __processOffer
self.__acceptOffer(offer)
File "/home/ubuntu/Desktop/AmazonFlexUnlimited420-master/lib/FlexUnlimited.py", line 523, in __acceptOffer
self.register_attestation()

TypeError: FlexUnlimited.register_attestation() missing 1 required positional argument: 'cert_chain'

Any help would be much appreciated. Used this one https://github.com/lumo93/AmazonFlexUnlimited420