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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 _read_packet(self):
 """ Reads and decodes a single packet Reads a single packet from the device and stores the data from it in the current Command object """

        # Grab command, send it and decode response
        cmd = self._commands_to_read.popleft()
        try:
            raw_data = self._interface.read()
            raw_data = bytearray(raw_data)
            decoded_data = cmd.decode_data(raw_data)
        except Exception as exception:
            self._abort_all_transfers(exception)
            raise

        decoded_data = bytearray(decoded_data)
        self._command_response_buf.extend(decoded_data)

        # Attach data to transfers
        pos = 0
        while True:
            size_left = len(self._command_response_buf) - pos
            if size_left == 0:
                # If size left is 0 then the transfer list might
                # be empty, so don't try to access element 0
                break
            transfer = self._transfer_list[0]
            size = transfer.get_data_size()
            if size > size_left:
                break

            self._transfer_list.popleft()
            data = self._command_response_buf[pos:pos + size]
            pos += size
            transfer.add_response(data)

        # Remove used data from _command_response_buf
        if pos > 0:
            self._command_response_buf = self._command_response_buf[pos:]