The following line returns an error:
self.m, self.userCodeToUserNameList, self.itemsList, self.userToKeyHash, self.fileToKeyHash = readUserFileMatrixFromFile
Just slice the last one out:
self.m, self.userCodeToUserNameList, \ self.itemsList, self.userToKeyHash, \ self.fileToKeyHash = readUserFileMatrixFromFile(x,True)[:-1]
EDIT after TigerhawkT3's comment :
Note that this works only if the return object supports slicing.