Attempt to feed an incoming CAN frame into the state machine

def feed(self, can):
        """Attempt to feed an incoming CAN frame into the state machine"""
        if not isinstance(can, CAN):
            raise Scapy_Exception("argument is not a CAN frame")
        identifier = can.identifier
        data = bytes(can.data)

        if len(data) > 1 and self.use_ext_addr is not True:
            self._try_feed(identifier, None, data)
        if len(data) > 2 and self.use_ext_addr is not False:
            ea = six.indexbytes(data, 0)
            self._try_feed(identifier, ea, data[1:])