How to get next state KalmanFilter

Hello. Thank you soo much for this code:). 
I want to predict five nex state of Kalmanfilter, but I dont understend how. I try to write new getter with kf.get_prediction, but I get an error "TypeError: unsupported operand type(s) for *: 'NoneType' and 'int'",because B is  'NoneType'