Initialize or reinitalize all the deferred transfer buffers

        Calling this method will drop all pending transactions
        so use with care.

def _init_deferred_buffers(self):
        """
        Initialize or reinitalize all the deferred transfer buffers

        Calling this method will drop all pending transactions
        so use with care.
        """
        # List of transfers that have been started, but
        # not completed (started by write_reg, read_reg,
        # reg_write_repeat and reg_read_repeat)
        self._transfer_list = collections.deque()
        # The current packet - this can contain multiple
        # different transfers
        self._crnt_cmd = _Command(self._packet_size)
        # Packets that have been sent but not read
        self._commands_to_read = collections.deque()
        # Buffer for data returned for completed commands.
        # This data will be added to transfers
        self._command_response_buf = bytearray()