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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 stream_to_packet(data):
 """ Chop a stream of data into MODBUS packets. :param data: stream of data :returns: a tuple of the data that is a packet with the remaining data, or ``None`` """

    if len(data) < 6:
        return None

    # unpack the length
    pktlen = struct.unpack(">H", data[4:6])[0] + 6
    if (len(data) < pktlen):
        return None

    return (data[:pktlen], data[pktlen:])