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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 decode_value(stream):
 """Decode the contents of a value from a serialized stream. :param stream: Source data stream :type stream: io.BytesIO :returns: Decoded value :rtype: bytes """

    length = decode_length(stream)
    (value,) = unpack_value(">{:d}s".format(length), stream)
    return value