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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def close(self):
 """ Break reference cycles to allow instance to be garbage-collected. Raises if called on a submitted transfer. """

        if self.__submitted:
            raise ValueError('Cannot close a submitted transfer')
        self.doom()
        self.__initialized = False
        # Break possible external reference cycles
        self.__callback = None
        self.__user_data = None
        # Break libusb_transfer reference cycles
        self.__ctypesCallbackWrapper = None
        # For some reason, overwriting callback is not enough to remove this
        # reference cycle - though sometimes it works:
        #   self -> self.__dict__ -> libusb_transfer -> dict[x] -> dict[x] ->
        #   CThunkObject -> __callbackWrapper -> self
        # So free transfer altogether.
        if self.__transfer is not None:
            self.__libusb_free_transfer(self.__transfer)
            self.__transfer = None
        self.__transfer_buffer = None
        # Break USBDeviceHandle reference cycle
        self.__before_submit = None
        self.__after_completion = None